Many experiments have studied attraction errors in number agreement (e.g. ‘The key to the cabinets were rusty’). It has been noted that singular heads with plural dependents (attractors) trigger larger attraction effects than plural heads with singular attractors, and that in languages with morphological case, morphologically ambiguous attractors trigger larger effects (accusative plural forms coinciding with nominative plural were compared to unambiguous case forms). In Russian, the nominative plural forms of some nouns coincide not only with their accusative plural forms but also with the genitive singular. In one production and two comprehension experiments, such genitive singular forms were found to trigger larger attraction effects than morphologically unambiguous genitive plural forms. Accusative plural forms coinciding with the nominative plural were shown to be the most effective attractors. These results have implications for different models of attraction and for other discussions in morphology concerning ambiguity processing, different approaches to syncretism and the problem of lexical insertion.