One of the key issues in visual word recognition is the role of orthographic overlap in priming. However, most research investigating this topic has focused on priming with orthographic neighbors. In this study, we investigate priming effects of word-final letter overlap and their interaction with word frequency, prime duration, and morphology. In Experiment 1 with briefly presented primes (SOA=34 ms, N = 123), we obtained similar facilitation from non-morphological overlap (compel-TRAVEL) and inflectional suffix overlap (turned-CALLED), regardless of word frequency. In Experiment 2 when primes were fully recognizable (SOA=150 ms, N=123), only non-morphological overlap showed inhibition among lower frequency prime words. These results are inconsistent with predictions of the Interactive Activation model (McCelland and Rumelhart, 1981), and suggest (i) different weights of inhibition and facilitation depending on prime duration and morphological structure of words as well as (ii) the involvement of a reset mechanism in long SOA conditions.