This paper focuses on the effect of disgruntlement among those primary voters who supported U.S. presidential nomination losers. It analyzes the general election voting behavior of primary voters in the last five presidential elections in order to determine if differences exist between those supporters of the winning nominee in each party and backers of other candidates who also sought the nomination. A multivariate analysis of the determinants of voter turnout shows significant results only for the Democrats in 1972, when primary voters who supported candidates other than George McGovern were more likely to abstain in the general election. Taking into account the option of defecting to another party in November, both parties appear to have been plagued by a considerable amount of disloyalty on the part of supporters of candidates who failed to win the nomination, although for the Republicans this type of response is confined to the 1980 election. The existence of a third party or independent candidacy may be an important variable influencing the behavior of these disgruntled primary voters.