Although recent clinical research has emphasized the relationship between Tourette's syndrome (TS) and obsessive-compulsive disorder (OCD), coprolalia, the most dramatic of the TS symptoms, has not been described in DSM-III OCD. The case presented here shows that coprolalia can indeed occur in OCD. This finding further erodes the phenomenological distinction between these two disorders. It also supports the role of psychological factors in the genesis of tic symptomatology.