Summary:Previous polysomnographic (PSG) investigations have reported a rhythmic electromyographic (EMG) pattern (0.5‐3.0 cps) of leg movement activity in a subset of patients with neuroleptic‐induced akathisia (NIA). It has been suggested that this EMG pattern may represent a pathophysiological correlate of NIA and thus have clinical utility as an objective marker for this condition. We present preliminary measures of sensitivity and specificity for this EMG pattern as a diagnostic marker for NIA for 26 neuroleptic‐treated patients. The EMG marker yielded a diagnostic sensitivity of 68.9% and a specificity of 70.0%, falling just short of statistical significance (Fisher's exact test p = 0.06). Quantitative analysis of the EMG pattern revealed a significant positive correlation between the percentage of time the NIA marker occurred during wakefulness and corresponding chlorpromazine equivalent levels. Clinical demographic findings for true‐positive, false‐positive, true‐negative, and false‐negative groups are discussed. Overall findings suggest that this particular pattern of EMG marker activity observed in neuroleptic‐treated patients during PSG and EMG studies is valuable in facilitating the diagnosis and monitoring treatment of NIA.