Objective: The study was designed to examine the relationship of rthe severity of physical disease, perceived physical health, and social support to depression as well as the differential roles of instrumental and social support among the elderly in Taiwan. Method: During 2002, we conducted a cross-sectional survey by interviewing a random sample of 4049 elderly subjects enrolled in 1989 and followed up in 1993 and 1996. The present study successfully completed the follow up of 2125 subjects. Results: The results illustrated, (1) with depression as a dependent varialbe, by performing hierarchical regression analyses, severity of physical disease, percepved physical health, emotional social support would directly predict the level of depression. However, the interaction between the severity of physical disease and instrumental social support would influence the degree of depression. (2) Furthermore, we separated the subjects by severity of phisical disease into high and low groups, and performed hierarchical regression analyses a second time. The results showed that as to the group with high physical disease, the more instrumental social support they had, the lower degree of their depression. Regarding the group with lower severity of physical disease, instrumental social support would not significantly predict the level of depression. Conclusion: The results of the present study suggested that perceived physical health and emotional social support directly influenced the degree of depression, while the severity of physical disease would buffer the impact of the instrumental social support on depression among the elderly in Taiwan.