22-27The whole body ether extracts of a marine prawn Nematopaleamon tenuipes (PEP), two gastropods viz. Euchelus asper (EAE) and Hemifusus pugilinus (HPE), and acetone extract of a fish Rastrelliger kanagurta (MA), were tested for their effects on Delayed type Hypersensitivity (DTH) reaction and Plaque Forming Cell (PFC) assay. The Delayed type Hypersensitive reaction assay for HPE and PEP as well as MA showed stimulation but EAE was found to be less effective. In the PFC assay HPE and MA showed immunostimulation whereas PEP and EAE showed immunosuppression. PEP was further resolved into two fractions, which were tested for in vitro lymphocyte proliferation assay as well as antiproliferative assay. It is concluded that the test extracts possess immunomodulatory property