We investigated whether adverse attachment experience might contribute to the development of obsessive-compulsive disorder (OCD). We interviewed 100 adolescents, 25 each with primary OCD, depressive disorder (DD), OCD plus DD and general population controls (CTRs) using the adult attachment interview to assess attachment experiences (AEs), including traumatic and adverse AE (TAE). Adolescents with OCD, OCD+DD and DD had little evidence of secure base/safe haven parental behaviour and their childhood attachment needs judged to be rejected as compared to the controls. Overprotection was not characteristic of OCD, and parents using the child for their own needs (elevated levels of involving/role reversal) occurred only in DD, with low levels in OCD, OCD+DD and CTR. Traumatic experiences, often multiple, and/or attachment related were reported significantly more often in the DD group, and was less common in OCD+DD, CTR and particularly in the OCD group. In OCD, little TAE was reported and adverse AE were less serious and seem unlikely to contribute directly to OCD aetiology. In DD and to some degree in OCD+DD serious AE/TAE may have some etiological significance for the depressive states.