The aim of the present study was to determine the differences in epidemiological and clinical manifestations of breast cancer during the war in Croatia and in peacetime. 660 consecutive patients were recorded (656 female and 4 male patients) from Pozesko-Slavonska County. The changes in histopathological features were recorded in war period (1991-1995, 156 patients) and through two control periods, before the war (1981-1990, 282 patients) and after the war (1995-2000, first five months, 223 patients). The relative predictive value was calculated using chi 2-test. The survival was calculated according to Kaplan-Meier analysis of survival. The histopathological analysis showed an equal distribution of noninvasive cancer (in situ cancer) across periods. In the war period, the level of the most common invasive cancer, ductal breast cancer, was lower (57.7%), compared to control periods (71.2%:63.7%:68.2%). Opposite to that, invasive lobular cancer was more common in the war period (3.2%), compared to control periods (0.7%-1.3%). Furthermore, mixed cancer was also increased in the war period (7.1%) compared to control periods (0.7%-2.2%), as was medullar cancer (10.9% vs. 5.5%-5.9%). The study showed statistically significant differences in the survival of patients with different histopathological diagnoses (Log Rank = 47.49, df = 7, p < 0.0001), while the histological grade of tumor, as a predictive factor was not proved to be statistically significant (p > 0.05). This study confirmed the influence of war of war on histopathological incidence of some forms of breast cancer.