We conducted a prospective cohort study on subjects aged>or=70 years in an urban community to determine whether there is any association between lack of social support and depression status. Of the 2730 eligible subjects, 1178 participated and were interviewed in a Comprehensive Geriatric Assessment (CGA) in 2002. We investigated the five social supports items using the following questions: (i) do you have someone with whom you can consult when you are in trouble?, (ii) do you have someone with whom you can consult when your physical condition is not good?, (iii) do you have someone who can help you with your daily housework?, (iv) do you have someone who can take you to a hospital when you do not feel well?, and (v) do you have someone who can take care of you when you are ill in bed? The Geriatric Depression Scale was used to estimate depression status. The subjects were divided into two groups: depressive and non-depressive. Of 753 subjects classified as non-depressive, 475 also took part in a CGA in 2003 and 278 dropped out. We calculated the risk of depression status in the elderly without social support. Lack of social support items (i) and (v) were significantly associated with an increased risk of depression status. The multivariate odds ratios (95% confidence intervals) regarding the risk of depression status among the elderly without (i) and (v) social support items were 2.6 (1.2-5.3) and 3.0 (1.4-6.1), respectively. We also found the increase risk of depression status with lack of social support item (v) was significantly different for different sexes and for different pain conditions. We conclude that there is a significant increase in the risk of depression status associated with the lack of social support in Japanese elderly people in an urban community.