A semiautomatic electronic system for counting blood cells in veterinary haematology (Sysmex F-800) was evaluated. A total of 100 samples of canine blood were analysed. The results for leucocyte (WBC), erythrocyte (RBC), and platelet (PLT) counts, the haemoglobin concentration (Hb), and haematocrit value (Hct) obtained using the autoanalyser were compared with those obtained using a manual method as a reference. The results show very high levels of correlation for WBC (r = 0.96), Hb (r = 0.97) and Hct (r = 0.95) and high levels for RBC (r = 0.85) and PLT (r = 0.72). The precision is satisfactory in all the parameters studied with the exception of the platelet count (CV = 10.2%) where it is unsatisfactory. Taking into consideration the margin of error associated with manual cell counting methods, we conclude that this haematological analyser is sufficiently accurate for work with blood samples from dogs.