It is not unusual to tacitly conflate conjectured inhibitory processes in cognition with inhibitory neural mechanisms. Here, we investigate whether resolution of memory interference, which is thought to entail cognitive inhibition, could be modulated by systemically administered GABAergic pharmacons in non-human primates.Twelve healthy adult rhesus macaques had been extensively trained in the PAL object-location working memory task on the Monkey CANTAB touchscreen test device. In each trial of the PAL task, the animals had to recall the locations of 3-7 distinct sequentially presented schematic visual stimuli from a large, 800-item stimulus pool. Between-trial interference was introduced in the task by recylcling one stimulus from the 1st, 4th, 8th or 16th previous trial. This stimulus recurrence successfully elicited a strong proactive interference effect: a 20-30% performance decrement was observed for a memory item recurring from the previous trial, which gradually tapered off if the interfering memory came from earlier trials. The benzodiazepine diazepam was administered intramuscularly 5 minutes before the 70-minute PAL sessions in 6 doses between 0.1 and 1 mg/kg against vehicle control in three experiments involving 8 animals in a within-subject design. While diazepam strongly, dose-dependently decreased performance in the PAL task, it did not modulate the interference effect.To conclude, the present results do not support the hypothesis that cognitive inhibitory processes involved in the resolution of memory interference would be mediated by GABAergic inhibitory neurotransmission.