The major differences of the autoanalyser Technicon H*2 with regard to the H*1, booth manufactured by the same firm, are the former's higher working speed, over one hundred samples per hour, its hydraulic changes and a new type of samples. This system provides cell counts, leucocyte differential count (LDC) and distribution graphs for cell volume, haemoglobin, platelets and leucocytes. Its accuracy was studied with regard to H*1 and reference methods, along with the precision, linearity, carry-over, necessary LDC revisions and LDC sensitivity, specificity and efficiency. Very good accuracy (r greater than 0.9) was found when except comparing H*2 with the other machine and the reference methods, except for MCHCH and basophil count. The linearity of results was good (r greater than 0.998) and the percentage of carry-over was less than 5% in all cases. Twenty one per cent of hospital patients (HP) and 8% of outpatients (OP) needed revision of LDC. False negative LDC appeared in 0.4% of HP and in 0.3% of OP. LDC sensitivity, specificity in H*2 have solved the problems of H*1, improving the performances and working velocity of the system.