Bleeding on probing and the presence of deep periodontal pockets are considered to be the best site-specific indicators for periodontal disease progression during the maintenance phase of periodontal therapy. A major emphasis of supportive periodontal care (SPC) programs, therefore, has been the control of bleeding pockets. This investigation retrospectively evaluated the changes in the prevalence of bleeding on probing, periodontal pockets, bleeding periodontal pockets and the prevalence of tooth loss in a random sample of 273 periodontal patients participating in a supportive maintenance care program at a University Clinic. During an observation period of 67+/-46 months (range 5 months to 23 years), the overall incidence of all causes of tooth mortality was 0.23+/-0.49 teeth per patient per year of observation. 56% of subjects, however, did not experience any tooth loss, while less than 10% of patients lost more than 3 teeth. Thus, participation in the SPC program was effective in preventing tooth loss in the majority of patients. During the SPC period, however, a significant increase in the prevalence of periodontal pockets, and of bleeding on probing positive periodontal pockets, in particular, was observed. At completion of active periodontal therapy, 56.4% of patients were free from bleeding pockets. This decreased to a mere 13.6% at the latest SPC evaluation. The observed increases in the number of bleeding pockets was significantly associated with: longer times since completion of active periodontal therapy, more advanced periodontal diagnosis, higher %s of bleeding sites in the dentition, cigarette smoking, lack of inclusion of periodontal surgery in the active treatment phase, tooth loss, and the response to the active phase of periodontal treatment. The data presented in the paper indicate that the observed increase in the prevalence of bleeding pockets and tooth loss was not homogeneously distributed in the studied SPC population. Rather, high risk groups of individuals could be identified. It is suggested that better knowledge of risk indicators may lead to improved and more efficient risk management efforts during periodontal maintenance care.