This study examined the prevalence and clinical features of ICD-10-defined neurasthenia (NT) in Chinese-Americans and its relations to other psychiatric disorders. In this community epidemiological survey, the enhanced Composite International Diagnostic Interview [CIDI], with a supplemental NT module, was administered to 1,747 Chinese-Americans, selected with a stratified cluster sampling method. The SCL-90-R was also used for measuring psychiatric morbidity and symptoms. Dimensions of social stress and social support were measured by established instruments. A total of 112 ICD-10 NT subjects (6.4%) were identified. Of these, 63 (56.3%) did not experience any current and lifetime DSM-III-R diagnoses, yielding a 12-month or lifetime prevalence rate of "pure" NT of 3.61%. This rate was much higher than any of the other psychiatric disorders in this sample. Compared with normal subjects, "pure" NT subjects had significantly higher SCL-90-R total and factor scores, experienced more psychosocial stress, and perceived less social support (P < .05 or .01). Compared with subjects with depression and anxiety disorders, "pure" NT cases reported significantly less SCL-90-R psychological symptoms (P < .05 or .01), but had a strikingly similar elevation in the somatization subscale score. These data suggest that NT is a distinctive clinical condition overlapping only partially with the other better recognized diagnostic entities. In view of its high prevalence and the salience of its impact on the health of those afflicted, it is imperative that concerted research efforts be made to further elucidate the temporal stability, natural course, and outcome of such a condition.