Background. Dutch (ex-)servicemen were deployed in the 1992–3-peace operation UNTAC in Cambodia. Since their return, they have voiced concerns about the health consequences of their service and they have reported symptoms such as fatigue and cognitive problems. The natural course of symptoms in Dutch Cambodia veterans was evaluated in a prospective study.

Methods. At 18-months follow-up, a questionnaire was sent to 354 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, post-traumatic stress disorder, trait-anxiety, self-efficacy and causal attributions, was used to evaluate predictors for self-reported improvement and low levels of fatigue at follow-up.

Results. At follow-up, 19% of the respondents 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.

Conclusions. Self-reported improvement was reported in a considerable percentage of Cambodia veterans, whereas another substantial percentage of Cambodia veterans 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 seem to bear importance for Gulf War veterans.