Based on an agreement between the Haematological Society of the J. E. Purkyně Medical Association and SEKK in 1994 nationwide external quality control of haemograms was started. A leading group was established comprising representatives of the professional society, representatives of SEKK, expert laboratories and the National control and reference laboratory. It was agreed to implement every year four cycles of haemogram evaluation, four cycles of evaluation of peripheral blood smears and two cycles of reticulocyte assessment. Every cycle comprised two control samples. Results where both samples had the same reading were considered correct. All participants who met the conditions of attendance were given a certificate on participation, participants who assessed correctly the haemogram were given an additional certificate for every correctly assessed value. The results are summarized in figures and commented. Regular external control of results of laboratory examinations increases the trustworthiness of the health system. There are so far no legal provisions in the CR concerning external quality control of laboratory examinations.

        Key words: external quality assessment, blood count, reticulocytes estimation, blood smear evaluation