The MESAM 4 system, developed to monitor breathing sounds, heart rate, arterial oxygen saturation (Sao2) and body position, was proposed as a screening method for obstructive sleep apnoea (OSA). The aim of the study was to assess the accuracy of hand-scoring versus automatic-scoring in screening for obstructive sleep apnoea. The study population consisted of 56 patients, 51 males, and 5 females, mean age 47 +/- 10 yrs, suspected of having obstructive sleep apnoea. Full polysomnography and MESAM 4 recordings were performed simultaneously. The apnoea+hypopnoea index was hand-scored in polysomnography and in MESAM 4. The hand-scoring in MESAM 4 was based on analysis of breathing sounds, heart rate and Sao2 changes taken together. The automatic-scoring system of MESAM 4 calculated oxygen desaturation index, heart rate variation index and intermittent snoring index. The diagnosis of obstructive sleep apnoea (apnoea+hypopnoea index > or = 10) was established by polysomnography in 37 patients. Sensitivity and specificity of hand-scored MESAM 4 diagnosis were 100 and 63%, respectively. Sensitivity and specificity of MESAM 4 diagnosis with automatic-scoring were: from oxygen desaturation index 100 and 27%; from heart rate variation index 81 and 74%; and from intermittent snoring index 92 and 16%, respectively. We suggest that hand-scoring of MESAM 4 is more accurate than automatic-scoring in screening for obstructive sleep apnoea.