Fifty-three chronic fatigue syndrome patients treated at a complementary medical centre were assessed over 12 months. Measures included the Chalder Fatigue scale, the General Health Questionnaire (GHQ) and positivity in illness (Silver Lining Questionnaire, SLQ). The SLQ measured at 6 and 9 months predicted (p < .01) mental (but not physical) fatigue at 12 months independently of current mental fatigue, initial mental fatigue, duration since diagnosis and time between start of treatment and entry to the study. The GHQ did not predict fatigue at any time point. The results suggest that a caring therapeutic intervention increases positive interpretations of illness prior to improvements in mental fatigue, but that positivity does not play a causal role in the reduction of fatigu