The aim of the present cross-sectional study was to compare love of life between three Iranian samples: multiple sclerosis patients, psychiatric outpatients, and a non-clinical sample of university students. The sample was a convenience sample of 496 individuals in Tehran, Iran, who completed the Love of Life Scale (LLS). The LLS scores were not significantly associated with age for the combined sample. The effects of sex and sex-by-group were not statistically significant. The LLS scores for the multiple sclerosis patients and university students were similar and significantly higher than the LLS scores of the psychiatric outpatients. Therapists should take this into account when working with psychiatric patients.