A multiple choice questionnaire was submitted to medical technologists in three medical laboratories, at varying times after obtaining an EN 45001 accreditation. A large majority (85-90 per cent) considered that their workload was increased by the accreditation process. In two laboratories, the technologists did not think that the accreditation process had improved the quality of the results. The major advantages were the fact that everything was traceable, that the technologists felt more sure about the procedures to follow, received more responsibilities and had a better knowledge of the tests they performed. The major disadvantages were the increased paperwork, discrepancies between the procedures and the reality, the fact that more attention is paid to the formalities than to the quality of the results and that the accreditation process decreased the adaptability. The number of advantages mentioned seemed to increase with the interval since the accreditation. A small majority of the technologists preferred working in an accredited laboratory than in a non accredited one.