The incidence of "pure" obsessive-compulsive disorders in the clinical population was found to be around 1.2 percent for a clinical sample record--stretching over a 2.5-year period--of around 2500 adolescents in a German child and adolescent psychiatry clinic. Over a 3-month period (time-frame) a sample of 350 new entries to the clinic were given a comprehensive series of questionnaires [Child Behaviour Checklist (YSR), Achenbach, 1991; Symptom Checklist (SCL-90-R)] and clinical assessment measures of socio-psychological, medical and educational attitudes (Englert and Poustka, 1995). Two groups of low and high trait compulsive individuals were generated (using the Symptom Check List, SCL-90-R) and socio-demographic and individual differences examined between these groups. Females were more likely than males to display high compulsive scores. Self-injurious behaviour was higher among the high compulsive group. There was no difference found in cognitive functioning, nor in family functioning, between the low and high trait compulsive groups. Multiple regression analyses using trait compulsivity as a dimensional trait (outcome variable) revealed the significant determinants were anxiety, depression, aggressiveness, phobic anxiety and psychoticism. Furthermore, the SCL Scales most predictive of compulsivity were depression, anxiety, aggression, phobic anxiety and psychoticism. Almost one-half of our patients displayed marked or full recovery after treatment and another 42 percent showed partial improvement (relief of symptoms in terms of reduction of frequency and intensity). The implications for future research are discussed. (Contains 6 tables.)