Background: Lack of mobility and motor impairments can intensify mental health problems in the elderly. Muscle weakness is one of the most important cause of fall in the old individuals. Muscular performance is regarded as one of the significant components of quality of life in older adults. Aim: This study aimed to investigate the effect of resistance training using Thera-Band on muscular strength and quality of life among the elderly. Method: This randomized clinical trial was conducted on 70 elderly people referring to the health centers of Mashhad in 2016. The participants were randomly assigned into two groups of intervention and control. The intervention group was subjected to lower- and upper-extremity resistance training with Thera-Band performed two thirty-minute sessions a week for six weeks. However, the control group did not receive any training. Data collection was performed using a dynamometer and the short version of the World Health Organization Quality of Life. The data were analyzed in SPSS version 16 using independent t-test, Mann-Whitney U test, paired t-test, Chi-square test, and exact Chi-square. Results: The mean ages of the individuals in the intervention and control groups were 69.7±6.1 and 77.2±6.2 years, respectively. After intervention, the mean scores of quality of life (P>0.001) and muscular strength in the upper and lower extremities (P>0.001) were significantly higher in the intervention group than those in the control group. Implications for Practice: Resistance training with Thera-Band could enhance muscular strength and improve quality of life in the elderly. It was concluded that the promotion of this exercise program could have a positive effect on the muscular strength and quality of life among this population