BACKGROUND Periodic limb movements in sleep (PLMS) are an increasingly pervasive disturbance for aging adults. The aims of this experiment were: (a) to describe the index of periodic limb movements in sleep (myoclonus index [MI] in elderly subjects with complaints of poor sleep or depression (N = 22; 68 +/- 5.5 SD years); and (b) to correlate MI with sleep history, depression scores, and objective and subjective indices of sleep. METHODS Sleep and leg movements were assessed for 5 consecutive nights. Between-subjects, nonparametric correlations were examined between mean MI and sleep history, depression scores, and objective and subjective sleep characteristics. Associations among within-subject night-to-night variabilities of MI, objective, and subjective variables were examined with repeated measures ANCOVA, entering MI as a covariate. RESULTS A remarkably high level of MI was found (median 25.8 events per hour; 86% of subjects > 5). Nevertheless, no associations were found between MI and sleep disturbance measures. CONCLUSIONS These results extend previous reports that PLMS are remarkably persuasive in elderly volunteers and support other reports questioning whether there is a distinct PLMS syndrome.