To test current hypotheses on the contribution of the basal ganglia (BG) to motor control, we examined the effects on visually-directed reaching of muscimol-induced inactivations in the skeletomotor region of the internal globus pallidus (sGPi). Injections were made in 2 monkeys trained to perform four out-and-back reaching movements in quick succession toward four randomly-selected targets locations. Following sGPi inactivations (n=18): (1) Peak velocity and acceleration were decreased in nearly all sessions whereas movement duration lengthened inconsistently. (2) Reaction times were unaffected on average, although minor changes were observed in several individual sessions. (3) Outward reaches showed a substantial hypometria that correlated closely with bradykinesia, but directional accuracy was unaffected. (4) End-point accuracy was preserved for the slow visually-guided return movements. (5) No impairments were found in the rapid chaining of out-and-back movements, in the selection or initiation of four independent reaches in quick succession, or in the quick on-line correction of initially mis-directed reaches. (6) Inactivation-induced reductions in the magnitude of movement-related muscle activity (EMG) correlated with the severity of slowing and hypometria. There was no evidence for inactivation-induced alterations in the relative timing EMG bursts, excessive co-contraction, or impaired suppression of antagonist EMG. Therefore, disconnecting the BG motor pathway consistently produced bradykinesia and hypometria, but seldom affected movement initiation time, movement guidance, the capacity to produce iterative reaches, or the ability to abruptly reverse movement direction. These results are discussed with reference to the idea that the BG motor loop may regulate energetic expenditures during movement (i.e., movement "vigor").