When a saccade occurs during a vergence movement, the amplitudes of the saccades in the two eyes may be markedly unequal (Ono, Nakamizo & Steinbach, 1978; Kenyon, Ciuffreda & Stark, 1980). This results in a large increase in vergence velocity, regardless of the direction of the saccade or vergence movement. The observation of unequal saccades in the two eyes has led to speculation that humans retian circuitry which allows relatively independent control of the movements of the two eyes (Enright, 1984). This hypothesis is notable because, if it were correct, it would require an extensive revision of our basic models of oculomotor control systems. We report experiments which suggest an alternative hypothesis: saccadic facilitation of vergence results from the interruption of inhibition of vergence burst neurons by pontine omnipause neurons, which are involved in initiating saccades. © 1995 Elsevier B.V.