Renal transplant recipients or patients on dialysis have a greater risk to infections, and possibly have a reduced response to vaccines. The aim of this study was to determine the antibody response to the primary vaccination of 23-valent pneumococcal capsular polysaccharide vaccine (PPV23) in renal transplant recipients who received immunosuppression therapy. A total of 66 patients with renal insufficiency, who referred to a single center for renal transplantation, were enrolled to this prospective study. A group of healthy subjects (including 40 individuals) were served as the control. All patients and individuals in control group received a single dose of unconjugated pneumococcal polyvalent vaccine intramuscularly and serum samples were obtained prior to, 4 weeks and 3 months respectively after the vaccination. Specific antibodies against whole pneumococcal antigens were measured using enzyme-linked immunosorbent assay. The results showed that among 66 vaccinated patients with renal insufficiency, 14 (21%) patients were found to be hyporesponsive to polysaccharide antigens. In this group of patients with reduced IgG response, the geometric mean titer of pre-immunization, post-immunization and absolute increase of antibody levels were significantly lower than those patients with normal antibody production. No significant differences were detected in specific antibody levels to S. pneumoniae between healthy control subjects and renal transplant recipients when patients with reduced IgG response were excluded. The majority of renal allograft recipients undergoing treatment with immuno­suppressive drugs showed an antibody increase after vaccination, however, the antibody response in this group was weaker than the control group. The results suggest that the currently available 23-valent pneumococcal polysaccharide vaccine is effective to produce a significant immune response in renal transplant recipients, and immunosuppressive therapy including prednisone, Cellcept and Sandimmune may reduce the antibody responses following pneumococcal vaccination but do not significantly impair the antibody response.