The aim of this study was to evaluate demographic and polysomnographic characteristics of positional (PPJ) and non-positional obstructive (NPP) sleep apnea (OSA) patients in 2077 OSA patients diagnosed in our Sleep Disorders Unit during a period of 10 years. An OSA patient is defined as positional if he has twice as many or more breathing abnormalities (apnea and hypopneas) while he sleeps in his supine posture compared to the lateral ones. Of the 2077 OSA patients, 1118 (53.8%) were positional and 959 (46.2%) were non-positional. No age differences were found between these two groups of patients. However, NPP were heavier and thus had a higher BMI than PP. PP had fewer and Less severe breathing abnormalities during sleep compared to NPP and thus, they enjoyed better sleep quality expressed by higher percentages of stage 2, 4 and 3+4 as well as a lower amount of short arousals than NPP. Also, PP patients are less sleepy during daytime hours than NPP. During the Multiple Sleep Latency Test (MSLT), NPP fall asleep faster in every nap than PP patients. No differences between these two patient groups were found for any parameter of Periodic Limb Movement Disorders. AHI and BMI are independently but inversely related to positional dependency. As AHI and BMI increase, the Likelihood to be a positional patient decreases. NPP have breathing abnormalities in the supine and lateral postures, thus, for them without question, CPAP is the treatment of choice. Since avoiding the supine posture during sleep may significantly improve the sleep quality and daytime alertness of many positional patients, it is imperative to carry out a high-quality study to evaluate if this is a real therapeutic alternative for many positional patients.