A 1-year follow-up of military members who received either early ankle mobilization or cast immobilization following a moderate or severe lateral ankle sprain was conducted to determine the long-term effects between these two forms of conservative treatment. Functional job- and sports-related disabilities together with subjective complaints were assessed. A significantly large proportion (44%) of all subjects were symptomatic at follow-up. Those receiving early ankle mobilization had slightly more residual subjective complaints compared with those receiving cast immobilization. There was, however, little effect on functional job- or sports-related disability, the early mobilization group having slightly fewer functional problems. There was no difference in subjective complaints or functional limitations by the degree of injury for moderate or severe lateral ankle sprains.