Obesity is recognized as playing an important role in causing snoring and in turning simple snoring into obstructive sleep apnea syndrome (OSAS). From our series of patients with sleep disturbances, we studied a group of 43 normal-weight snorers in whom we detected a significant number of OSAS episodes. An articulated diagnostic protocol was adopted, and Müller's maneuver was extensively applied. The resulting data were compared to data from a group of 43 obese patients from the same series. The major risk factor for developing OSAS in normal-weight snorers appears to be anatomic abnormalities, in particular, septal deviation and base of tongue hypertrophy. Soft palate hypertrophy alone is not enough, although in obese snorers it can produce a sleep disorder. The normal-weight snorer needs to be thoroughly investigated because of the significant risk of developing OSAS and for the detection of multiple concomitant sites of obstruction.