The objective of this research was to evaluate quality of life and impact of daytime sleepiness in patients with Sleep Apnea/Hypopnea Syndrome (SAHS). 100 subjects were included: 50 patients with OSAS and 50 healthy subjects, who responded to the Short Form-36 Health Survey (SF-36), the Functional Outcomes of Sleep Questionnaire (FOSQ) and the Epworth Sleepiness Scale (ESS). The comparison between clinical and control group showed statistically significant differences (p < 0.05) in most of the variables studied. The results found that body mass index, apnea-hypopnea index and desaturation index were the most important affecting factors. This study shows the great impact OSAS has on the quality of life of patients.