The paper presents the method of measurement of the particulate matter in the exhaust gases of a Rolls-Royce Allison 250-C20B turbine engine in the aspect of the assessment of the technical condition of the bearing seals of the rotor shaft. The tests were carried out on 4 engines using a Horiba TEOM 1105 PM analyzer fitted with a mini dilution tunnel – Micro Diluter 6100. The paper also presents the method of determining of the engine technical condition index (bearing seals) developed by the authors based on the data obtained from the measurements. The reliability of the obtained results has also been subjected to evaluation.