Clinically derived measures of the initial course of episodes might reflect a process of sensitisation in affective disorder. However, the clinical consequences of such measures have not been investigated. The predictive effect of measures of the initial course of episodes was investigated in relation to the subsequent risk of alcoholism, dementia, death and suicidal attempts/suicide in a case register study including all hospital admissions with primary affective disorder in Denmark from 1971 to 1993. A total of 8737 patients with more than one episode were included in the analyses. A short period between initial episodes of the illness, reflecting a great intensity of illness, predicted increased risk of subsequent development of dementia, and for unipolar patients, decreased risk of subsequent alcoholism. Surprisingly, a progressive course, with decreasing intervals between initial episodes of the illness, had no predictive effect. Similarly, no predictive effects on the risk of death or suicidal acts could be demonstrated with any measure of the initial course of episodes.