This study evaluated the quality of reporting electromyography in studies evaluating the masticatory muscles published during 2004. Several electronic databases were searched. Abstracts and later articles were selected by a consensus from the five reviewers. An adaptation of the methodological checklist published by the International Society of Electrophysiology and Kinesiology (ISEK) was used. The following information regarding electrodes was reported on the 35 finally selected articles: location (94.3%), interelectrode distance (48.6%), and material (42.9%); detection and amplification: amplification type (54.3%), gain (25.7%), low high pass filters (60%) and cut-off frequencies (60%); electromyography (EMG) processing: sampling rate (74.2%), rectification (46.6%), root-mean square (RMS) (39.2%); number of bits and model of A/D card (17.1%); and normalization procedure (40%). Reasons for the poor reporting are discussed. Because of the general poor quality of reporting of the analysed studies, findings of studies using surface electromyography of masticatory muscles should be interpreted with caution.