The present research focused on the evaluation of bioactive principles from the locally cultivated two medicinal plants: Cissus repens Lam. (Wa-round-chin) and Boesenbergia rotunda (L.) Mansf. (Seik-phoo-chin) including the phytochemical analyses, isolation and structural elucidation of organic compounds and biological activity screening such as antimicrobial activity, antioxidant activity, cytotoxicity test, antitumor activity and antiproliferative activity. The whole plants of C.repens and aerial parts and rhizomes of B.rotunda were collected from Kyauk Tan Village, Bago Region and their respective scientific name has been identified at Botany Department, University of Yangon. The preliminary phytochemical tests revealed the presence of alkaloids, carbohydrates, flavonoids, glycoside, organic acid, phenolic compounds, saponins, steroids, tannins and terpenoids in the whole plant of C.repens (WRC), aerial parts and rhizomes of B.rotunda (SPCA and SPCR). Determination of nutritional valves of WRC, SPCA and SPCR haveP also been carried out by AOAC method, resulting 3.11%,3.28% and 4.49% of moisture, 6.80%, 14.75% and 7.00% of ash, 12.18%,9.23% and 6.82% of protein, 13.73%, 28.54% and 12.24% of fiber, 7.90%, 5.81 % and 3.62% of fat, 56.28%, 38.39% and 65.83% of carbohydrate respectively based on the dried samples. In addition, some soluble matter contents of the samples were also analysed using PE, EtOAC, CH3COCH3, EtOH and water as solvents. On silica gel column chromatographic separation, eight compounds were isolated from PE extract of WRC, EtOAc and CHCl3 extracts of SPCR, characterized by some physical and chemical properties and structurally identified by the combination of UV, FT IR, IH NMR, 13C NMR, 2D NMR and ESI MS spectroscopic methods and also by comparing with the reported data. The compounds isolated from PE extract of WRC were identified to be friedelin (A, 0.014 %, m.pt. 258-259 °C) and friedelinol (B, 0.008 %, m.pt. 278-279° C). Two compounds isolated from EtOAc extract of SPCR were identified to be β-sitosterol (C, 0.26 %, m.pt.138-140 ° C) and β-sitosterol-β-D-glucoside (D, 0.9 %, m.pt-272-274 °C) whereas the compounds obtained from CHCl3 extract of SPCR were pinostrobin (E, 0.26 %, m.pt. 96-98 °C), 4', 7-dimethylkaempferol (F, 0.25 %, m.pt 179-182 °C), galanal A (G, 0.43 %, m.pt. 165-167 °C) and galanal B (H, 0.83 %, m.pt, 134-134.5 °C). The antimicrobial activity of PE, EtOAc, EtOH and MeOH extracts from WRC, SPCA and SPCR was screened on six microorganism such as Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus pumilus, Candida albicans and Escherichia coli by agar well diffusion method. All of these crude extracts have pronounced antimicrobial activity with inhibition zone diameters ranged between 13mm ~ 55mm in WRC, 14mm ~ 55mm in SPCA and 13mm ~ 35 mm in SPCR respectively. The MIC values of EtOAc extracts (24.4141 µg/mL, 2500 µg/mL) of WRC, (25000 µg/mL, 25000 mg/mL) of SPCA, (100000 µg/mL, 100000 µg/mL) of SPCR and some isolated compounds A-D [friedelin (12.5 µg/mL, 25 µg/mL), friedelinol (100 µg/mL, 100 µg/mL), β-sitosterol (25 µg/mL, 25 µg/mL), β-sitosterol-β-D-glucoside (100 µg/mL, 100 µg/mL)] of WRC, SPCA and SPCR were also determined against two species of organisms such as Staphylococcus aureus and Escherichia coli by agar well diffusion method. The antioxidant activity of ethanol and watery crude extracts of WRC, SPCA and SPCR and some isolated compounds (friedelin, friedelinol, β-sitosterol-β-D-glucoside) was determined by DPPH radical scavenging assay by using UV spectrophotometric technique. The order of radical scavenging activity was observed as SPCA> SPCR > WRC for ethanol extracts whereas the order of radical scavenging activity was SPCA> WRC > SPCR for watery extracts. The antioxidant potential of isolated compounds were found to be in the order of β-sitosterol-β-D-glucoside > friedelin. Friedelinol did not show % inhibition in the range of concentration 28.71-47.69 µg/mL, Ethanol crude extract of SPCR possessed mild cytotoxicity on brine shrimp. Its LD50 was determined to be 370.50 µg/mL, after 24 hours while the other crude extracts did not exhibit their cytotoxic effect up to the optimum dose of 1000 µg/mL, Antitumor activity of ethyl acetate, ethanol and methanol extracts of WRC, SPCA and SPCR and some isolated compounds A-D (friedelin, friedelinol, β-sitosterol, β-sitosterol-β-D-glucoside) were also tested on tumor produced bacteria using PCG (Potato crown Gall) test. From this experiment, all of the test extracts from all samples were significantly found to inhibit the formation of tumor in the dose of 0.2 g/disc. Among test compounds, friedelin, β-sitosterol and β-sitosterol-β-Dglucoside showed to prevent the tumor formation with the dose of 0.1 µg/disc. Moreover, antiproliferative activity of MeOH extract of WRC, SPCA and SPCR, CHCl3) extract of SPCR and four isolated compounds (pinostrobin, 4', 7-dimethylkaempferol, galanal A and galanal B) was determined by using ten human cancer cell lines. The antiproliferative activity of four extracts were found to be in order of SPCA (MeOH extract) > SPCR (CHCl3 extract) > SPCR (MeOH extract) > WRC (MeOH extract) against lung (LK-2), lung (A549), stomach, breast human cancer cell lines and normal human fibroblast. The order of antiproliferative activity of three extracts were observed as SPCA (MeOH extract> SPCR (MeOH extract) > WRC (MeOH extract) against colon, liver, cervix, leukemia and prostate human cancer cell lines. Among the isolated compounds, galanal A and galanal B were found to be more potent than pinostrobin and 4',7-dimethylkaempferol in antiproliferative activity against lung (LK-2), lung (A549), stomach, breast human cancer cell lines and normal human fibroblast