Introduction. Diesel oil is a mixture of hydrocarbons. These compounds are widely used in everyday life. Oral exposures are most often accidental and affect mainly children, but they also happen in adults. Oral ingestion may lead to aspiration of pulmonary alveoli which may cause necrotizing pneumonia. Aim. The aim of the study is to assess te severity of diesel oil intoxication on an example of a presented case. Methods. The analysis of the clinical patient history and review of available literature. Results. A 27 year old patient was admitted to the toxicology department due to accidental diesel poisoning. Patient drank a small amount diesel oil, then suffered nausea and vomiting, which resulted in aspiration of diesel to respiratory system. During hospitalization focal necrotizing pneumonia was diagnosed. Patient was treated with intensive specific pharmacotherapy. On the 11th day of stay, the patient was discharged with recommendation of control in the pulmonological and toxicological clinic and chest x-ray examination in order to diagnose the suspicious oval change discovered in the right lobe during hospitalization. Conclusion. First toxicity symptoms are non-specific, so well collected anamnesis is crucial. Complications of hydrocarbon ingestion can be a threat to patient’s life. Due to rarity of the problem, there are no clearly defined treatment guidelines.