Objective: Sildenafil is a selective and potent inhibitor of cyclic guanosine monophosphate specific phosphodiesterase-5 and has anti-inflammatory effects. The aim of the study was to evaluate the effects of sildenafil on smoke-induced lung inflammation. Material and Methods: Twenty-nine Wistar-Albino rats were enrolled into 3 groups as control, smoker and sildenafil groups. Smoker and sildenafil groups were exposed to cigarette smoke for 2 hours per day for 8 weeks. Sildenafil 10 mg/kg/day was administered to the sildenafil group by nasogastric lavage after smoke exposure. The degree of lung inflammation was scored histopathologically for each group. Results: The inflammation score was 7.25 +/- 0.93 in the control group, 8.18 +/- 1.21 in the smoker group and 7.08 +/- 1.66 in the sildenafil group. There was a non-significant decrease of inflammation score in sildenafil group with respect to control or smoker groups. While there was no significant difference of oedema, hyperemia, hemorrhage and mononuclear cell infiltration scores among the groups, it was found that the thickness of interalveolar septum and alveolar distortion was decreased in sildenafil group. However this decrease was not statistically significant. Conclusion: This study suggests that sildenafil might reduce smoke-induced inflammation in rat lungs. Future studies are needed in order to investigate the clinical effectiveness of this finding in smoking related lung diseases.