The present study was carried out in order to determine the effect of lung resection on the frequency of infections in alloxan-diabetic rats. Adult female Wistar rats were injected with alloxan (40 mg/kg, iv) to induce diabetes mellitus (group D; N = 45) or with vehicle (1.0 ml/kg, iv) to be used as controls (group C; N = 45). Thirty-six days after receiving alloxan both groups were randomly divided into three subgroups: no operation (NO; N = 15), sham operation (SO; N = 15), and left pneumonectomy (PE; N = 15). The rats were sacrificed 36 days after surgery and their lungs were examined microscopically and macroscopically. The occurrence of thoracic wall infection, thoracic wall abscess, lung abscess and pleural empyema was similar in groups D and C. In contrast, the overall infection rate was higher (P<0.05) in the diabetic rats (SO-D and PE-D subgroups, but not in the NO-D subgroup). Considering that the overall infection rate was similar in the SO-D and PE-D subgroups, we suggest that surgery but not pneumonectomy was related to the higher prevalence of infection in diabetic rats.