Evaluated the natural course of symptoms in Dutch servicemen who had been deployed in the 1992-93 peace operation in Cambodia in a prospective study. At 18-mo follow-up, a questionnaire was completed by 227 veterans who met a set case definition for symptoms in Cambodia veterans or who had sub-threshold scores. Initial measurement of fatigue severity, psychological well-being, depression, posttraumatic stress disorder (PTSD), trait-anxiety, self-efficacy, and causal attributions was used to evaluate predictors for self-reported improvement and low levels of fatigue at follow-up. 19% of the Ss reported complete recovery, 20% felt much better, 57% had the same complaints and 4% had become worse compared with their initial assessment. Self-reported improvement and less severe fatigue at follow-up were predicted by less severe fatigue at initial assessment and more perceived control over symptoms. Self-reported improvement was reported in a considerable percentage of Ss, whereas another substantial percentage of Ss continued to suffer with severe levels of fatigue and related symptoms. Predictors of improvement in Cambodia veterans and patients with chronic fatigue syndrome show similarities and also may bear importance for Gulf War veterans.