Earlier we have shown significantly more frequent B blood group and a significantly more rare O blood group of ABO blood group system in men aged under 45 years suffering from coronary atherosclerosis compared with these frequencies in the population of Lithuania. The aim of the study was to investigate the frequency of blood groups of ABO system in women with coronary atherosclerosis.The frequency of the ABO blood groups was examined in 441 women, suffering from coronary atherosclerosis, divided into two groups: I group - 109 women till 60 years old (mean age 55.1+/-4.8) and II group - 332 women aged over 60 years (mean age 68.1+/-5.0). For all patients coronary atherosclerosis was diagnosed by coronary angiography and confirmed during coronary bypass surgery. The frequency of the ABO blood group in the studied pts was compared with the frequency of the blood group in the control group of healthy blood donors (n=595). To evaluate the significance of data, we compared the frequency of ABO blood groups with the data in women long-livers (n=75, mean age 94.1+/-3.8). Earlier our studies showed that long-livers are an important antiatherosclerotic control group for evaluation of the genetic markers of atherosclerosis.The O blood group was found significantly more rarely in the women group I as compared to that of healthy donors group (28.4% vs 38.2%, p<0.04). The B blood group was significantly more often in group II (22.9% vs 15.0%, p<0.04) compared with the frequency of the B blood group in the healthy donors' group. In the long-livers' group the frequency of the B group was significantly more rare than in healthy donors (6.7% vs 15%, p<0.01) as well as in the groups of tested pts (20.2% and 22.9% respectively, p<0.01). We did not find any significant changes in the frequency of AB blood group in women with coronary atherosclerosis.The B blood group can be related with coronary atherosclerosis in women. The O blood group can possibly serve as a protective antiatherogenic factor in women. The A blood group is not a risk factor for atherosclerosis in women in Lithuanian population. Long-livers are an important antiatherogenic control group for evaluation of atherogenetic markers of coronary atherosclerosis.