Two-stage revision is the gold standard in treatment of TKA infection. Several risk factor as the type of microbical flora, presence of general and local comorbidity and the type of therapeutic protocol may influence the success rate of treatment. The aim of our study is to assess the impact of these factor on prognosis in two-stage revision in chronic periprosthetic knee infection. We treated 38 knees in 37 patients, with an overall recurrence of 23,5% (9 recurrences). Our series analisys shows that associated diseases can affect the final result, with recurrence of infection in 12% of patients with one risk factor and in 33% of patients with association of comorbidity, wherass any infection occurred if less than three comorbidity were present. We also detect a statistically significative higher rate of recurrence in presence of local risk factor and in infection sustained by methicillin-resistant germs or with poly-microbial flora. Presence of these factors significantly affect prognosis and should be taken into serious consideration in the decision process leading to appropriate treatment.