Abstract. Experiments formonitoring of changes in haematological parameterswere carried out in dogs after acute intoxicationwith the carbamate insecticide carbofuran (Carbosan 35 ST). The studies involved one control and 6 experimental groups of dogs (total n=42), treated once orally with increasing doses of the preparation via oesophageal probe: 0.525 mg/kg (experimental group I), 1.05 mg/kg (experimental group II), 2.1 mg/kg (experimental group III), 3.5 mg/kg (experimental group IV), 5.25 mg/kg (experimental group V) and 10.5 mg/kg (LD ), (experimental group VI), corresponding to 1/20, 1/10, 1/5, 1/3, 1/2 and LD , 50 50 oral doses for albino rats. Blood samples were obtained from v. antebrachi cephalica or v. jugularis in the course of 3 consecutive days prior to the treatment (hours -48, -24 and 0) and on post treatment hours 1, 3, 5, 7, 24 and 48 from all groups for analysis of blood cell counts (RBC), white blood cell counts (WBC), haemoglobin content (HGB), haematocrit (HCT), differential white cell counts (DWC) erythrocyte sedimentation rate (ESR). It was established that the tested carbamate insecticide caused decrease RBC, HGB and LYM, and increased the levels of WBC and banded neutrophils between post treatment hours 1 and 24; afterwards, the studied parameters regained the respective control values