Controversy surrounding the causation of symptom complaints after mild traumatic brain injury (MTBI) is reflected by the existence of alternative diagnostic criteria for postconcussional syndrome (PCS) in the International Classification of Diseases (ICD) and postconcussional disorder (PCD) in the Diagnostic and Statistical Manual of Mental Disorders-4th edition (DSM-IV). Previous studies of persisting symptoms have employed various symptom checklists rather than uniform criteria-based diagnoses. This is the first prospective study of persisting symptom complaints using the formal diagnostic criteria for PCD and PCS and comparing these criteria sets in terms of prevalence, relationship to potential compensation, and emotional/functional status. In this prospective study, an unselected series of adults with uncomplicated MTBI (N = 139) was assessed at 6 months postinjury with a brief neuropsychological battery and measures of psychiatric symptoms/disorders, social support/community integration, health-related quality of life, and global outcome. In parallel analyses, participants with PCD/PCS were compared to those without the disorder. Potential compensation was an equally significant factor in both criteria sets. Persistent PCS criteria were met 3.1 times more frequently than persistent PCD criteria. Significant racial differences in fulfilling PCD/PCS criteria were found. No differences in emotional/functional status patterns or global outcome were found between the criteria sets except for minor dissimilarities in the social/community integration domain. The results demonstrate that despite large differences in the frequency of patients meeting the two diagnostic criteria sets, a clear basis for preferring either the PCD or PCS criteria remains to be determined.