The purpose of this study was to estimate the prevalence of depression in patients with social anxiety disorder (SAD) and to assess the relationship between the severity of SAD symptoms and depression. Ninety-eight consecutive patients with generalized SAD according to DSM-IV criteria were included in a cross-sectional case-control study. Patients were referred to a psychiatric outpatient clinic in a general hospital in Saudi ArabiThe Liebowitz Social Anxiety Scale was used to estimate the severity of SAD. Fifty-eight (59%) of the patients with SAD had another current psychiatric disorder. Forty (41 %) patients had current depression, and 37 (92.5%) of them had it after SAD onset. Eleven of 16 patients with severe SAD (69%) had depression whereas only 29 of 82 of SAD patients with mild or moderate subtypes (35%) had depression. Patients with severe SAD were four times more likely to have depression than the patients with mild or moderate SAD even after controlling for confounding sociodemographic and clinical factors. Depression is common among patients with SAD, particularly the severe subtype. Early recognition and treatment of SAD, especially the severe subtype, may prevent the occurrence of depression. Prospective studies are needed to investigate the risk factors that may lead to depression in SAD.