Aspiration of gastric contents can cause serious lung injury, although the mechanisms of pulmonary damage are still not clear and means of amelioration of the pulmonary damage have been little investigated. The black cumin seed, Nigella sativa L. (NS) has been shown to have specific health benefits and the aim of the current study was to investigate the possible beneficial effects of NS on experimental lung injury in male Wistar rats after pulmonary aspiration of different materials. The rats were randomly allotted into one of six experimental groups (n = 7 per group): (1) saline control, (2) saline+NS treated, (3) Pulmocare (a specialized nutritional supplement given to pulmonary patients), (4) Pulmocare+NS treated, (5) hydrochloric acid, (6) hydrochloric acid+NS treated. The saline, Pulmocare and hydrochloric acid were injected into the lungs in a volume of 2 ml/kg. The rats received daily oral doses of NS volatile oil (400mg/kg body weight) by means of intragastric intubation for 7 days starting immediately after the pulmonary aspiration of the materials. After 7 days, the rats were sacrificed and tissue samples from both lungs were taken for histopathological investigation. To date, no similar study investigating the potential for NS treatment to protect against lung injury after pulmonary aspiration of materials has been reported. Our study showed that NS treatment inhibits the inflammatory pulmonary responses, reducing significantly (p<0.05) peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar macrophages, interstitial fibrosis, granuloma and necrosis formation in different pulmonary aspiration models. Our data indicate a significant reduction in the activity of inducible nitric oxide synthase (iNOS) and a rise in surfactant protein D in lung tissue of different pulmonary aspiration models after NS therapy. Based on our results, we conclude that NS treatment might be beneficial in lung injury and have potential clinical use. (C) 2009 Elsevier GmbH. All rights reserved.