Background: Since there has been no research on music therapy in a systematic way so far to develop motivation and hope in the course of treating individuals who are addicted to drugs, especially stimulant drugs whose use has increased in Iran, the present research was conducted to examine the effect of music therapy on the sense of loneliness and life expectancy in methamphetamine-addicted individuals who were attempting to quit. Methods: The research is pretest, posttest, and test and control groups. The research sample includes 30 methamphetamine-addicted individuals who were quitting in a midterm residential center in Sowme'eh Sara who were selected by convenience sampling and allocated to two control (N = 15) and experiment (N = 15) groups randomly. UCLA sense of loneliness scale and Schneider statistical questionnaire (1991) were used for data collection. Results: Studies showed that music therapy could reduce the symptoms related to the sense of loneliness and increased life expectancy (P < 0.001). Conclusions: It is concluded that mental health professionals can use group music therapy to improve sense of loneliness and life expectancy in methamphetamine-addicted individuals attempting to quit. Also, it is suggested that future research should investigate the effectiveness of group music therapy in improving other psychological constructs in addicted females and males who are attempting to quit.