Four visual lexical decision experiments using the masked priming paradigm tested for effects of prime word frequency and cumulative root frequency with primes varying in degree of morphological and orthographic overlap with free root targets in French. Experiments 1 and 3 showed that only high frequency morphologically related primes produce significantly faster response times compared to orthographic control primes. On the other hand, no significant orthographic priming effects were observed in the present study, except in Experiment 2 where the most frequent orthographic primes produced significantly more errors than the other priming conditions. In Experiment 4 similar levels of morphological priming were obtained to free root targets with high and low cumulative root frequencies. These findings are interpreted within the framework of a supralexical representation of morphological information in memory.