In order to elucidate a possible excess risk of lymphatic malignancies due to aircraft fuel exposure in the Swedish Armed Forces (SAF), a historical prospective cohort study was conducted. During a 9-year follow-up period, 3 cases of malignant lymphoma were detected versus 3.21 expected tumors of the lymphatic system (standardized incidence ratio (SIR) 93; 95% confidence interval (CI) 19-273) among 2,176 men. The overall SIR was 91 (CI 66-120), whereas the corresponding mortality ratio was only 54 (CI 42-68; p less than 0.001). In conclusion, no evidence was found for an association between military aircraft fuel and the occurrence of malignant lymphomas or other malignancies among exposed men in the SAF. For a definite risk assessment, further follow-up is necessary.