Diesel engine exhaust and blowby gases were sampled and analyzed for nitrosamines. Tenax-GC traps were used as collection media. Three different engines were sampled. Tenax-GC material used contained significant quanities of dimethyl nitrosamine as impurities. A cleaning procedure was developed to precondition the traps. No nitrosamines were detected in either exhaust or blowby down to levels of 90 pptr and 10 pptr respectively.