In a recent paper, Clahsen and Almazan (1998) reported a dissociation between unimpaired regular and impaired irregular past tense morphology in English Williams syndrome (WS). Our aim is to investigate whether these findings carry over to another language with different morphological systems. We present data on regular and irregular participles and noun plurals from 2 German WS subjects and 10 controls matching in mental age. For noun plurals, regular morphology is intact in WS, whereas irregular forms are impaired. A similar dissociation is observed for participles: while regular inflection is unimpaired, WS subjects, unlike controls, apply the regular suffix incorrectly to frequent irregular verbs. We discuss our findings against the current debate between connectionist and dualistic approaches to the language faculty.