Problems emerging from previous analyses of epenthesis in Japanese verbal endings are discussed and a crucial relationship between epenthesis and assimilation is argued. The focus is on the occurrence of /i/-epenthesis with certain root-final consonants. The analysis, which incorporates the view that assimilation is accomplished by means of autosegmental spreading, illustrates that epenthesis cannot split clusters that have undergone assimilation. Assimilation and epenthesis are seen as complementary, with epenthesis occurring where assimilation has not. (MSE)