Speech pause time (SPT)-the silent interval between phonations during automatic speech-is elongated during depressive episodes among endogenous depressives. Phonation time is unchanged. To follow up and expand earlier small-scale studies of these psychomotor findings we conducted a prospective determination of SPT among 24 unipolar (UP) depressives, 12 bipolar (BP) depressives, and 19 nondepressed controls. SPT was lengthened among both UP and BP depressives during their episodes. This elongation disappeared with clinical improvement. Nondepressed controls did not have longer SPT. During states of clinical remission, depressives and controls had comparable SPT values. Replications are required, but the measurement of SPT appears to be a useful, objective technique for identifying and monitoring psychomotor deceleration among depressives.