This study investigated inter-rater reliability for scoring periodic leg movements in sleep (PLMS) and related phenomena. Five highly experienced polysomnographic technologists each scored 24 nocturnal polysomnograms, the majority of which contained an appreciable number of PLMS. Results indicated high inter-rater reliability for some variables but more modest reliability for others. We discuss these findings in terms of efforts of standardization in polysomnographic scoring of sleep disorders.