Most research on relapse from exercise has investigated one relapse episode following a structured program. The present study examined the patterns and determinants of the lifetime history of relapse from exercise in a community population. Subjects were 1.811 randomly selected residents of San Diego, California who completed an extensive mailed survey. Subjects reported the number of times over their lifetime that they had exercised vigorously for at least six months and then stopped exercising for at least three months. Approximately 60% of subjects reported zero relapses, 20% reported one or two relapses, and 20% reported three or more relapses. Relapse histories of current exercisers and current nonexercisers were virtually identical. The most commonly reported reason for the last relapse was injuries for both nonexecisers and exercisers. Multiple regression analyses were used to identify correlates of exercise relapse history. These data indicate that cross-sectional surveys of exercise behavior are inadequate to characterize exercise behavior in a population, and injuries are probably a major cause of relapse.