Infectious complications, including pneumonia, remain one of the leading causes of morbidity and mortality in kidney allograft recipients. The aim of the study was to evaluate the relationship between pneumonia occurrence and treatment duration and recipient age, cause of native kidney insufficiency, dialysis duration, time between transplantation and onset, HLA matching, PRA immunosuppressive protocol, acute rejection incidence and treatment, kidney function at the pneumonia onset, as well as presence of comorbid conditions. One hundred and twenty pneumonia cases occurred in kidney allograft recipients transplanted between 1991 and 2000 with 12 to 120 months follow-up. Twenty five percentage of pneumonia episodes were diagnosed during the first posttransplant month, 25% between 2 and 6 months, and 25% at 0.5 to 3 years. Treatment duration measured from pneumonia onset to the study endpoint of recovery, which was defined as antibiotic withdrawal, show 50% of patient we cured after 15 days and 75% after 24 days of treatment. The risk of prolonged pneumonia treatment was associated with: second versus first kidney transplantation with RR = 2.3 (P <.02) and medians of treated time 28 versus 15 days; as well as serum creatinine level above 2 mg/dL (RR = 1.4; P <.098). Exposure to enhanced-potency immunosuppressive protocols including induction therapy with mono- or polyclonal antibodies increased the RR = 1.65 (P <.02), and lengthened the time to 18 versus 14 days. Maintenance immunosuppression with agents other than cyclosporine also enhanced the risk. (RR = 2.18; P <.068).