The Geriatric Depression Scale-15 (GDS-15) is a short, 15-item instrument specifically designed to assess depression in geriatric populations. Its items require a yes/no response. The Geriatric Depression Scale was first introduced by Yesavage et al. in 1983, and the short form (GDS-15) was developed by Sheikh and Yesavage in 1986. The aim of the current study was the standardization of the GDS-15 for use in Greece. Subjects were divided into Group A: 168 control subjects, and Group B: 103 patients suffering from clinically diagnosed depression. All were over 65 years of age. A score of 6/7 on the GDS-15 was found to be the best cut-off point for diagnosing depression in an elderly Greek population, with Sensitivity = 92.23 and Specificity = 95.24. GDS-15 manifests high internal consistency with Cronbach's alpha = 0.94, and all items seem to be equivalent. Factor Analysis of the GDS-15 revealed 4 factors: a cognitive (thought content), an affective, a functional, and a factor that reflects helplessness and fear for the future. The two diagnostic groups differed on all 4 factors scores at p-value <0.001.