Breast cancer is the most frequently diagnosed cancer in women. Treatment of breast cancer, such as chemotherapy and immunotherapy, can weaken the immune system of patients and increase the risk of serious complications if they become infected with the coronavirus. The aim of the research is to determine the impact of the COVID-19 pandemic on the number of diagnosed breast cancers in women at the Vinkovci General County Hospital over four periods, the pre-pandemic period, the first pandemic period, the second pandemic period and the post-pandemic period. 167 patients were included in the study. The data were collected from the archives of the General County Hospital in Vinkovci. There is no statistically significant difference (p>0.05) in the number and age (p>0.05) of patients throughout the four pandemic periods. The most common histological type of breast cancer is invasive breast cancer of no special type (IBC-NST), and the least common type of breast cancer with medullary characteristics and tubular invasive type. Contrary to expectations, in the pre-pandemic period there was the highest occurrence of metastases, and the most common tumor size was 2 cm in all four periods and does not differ between the investigated periods (p>0.05). In conclusion, in this study there is no significant difference in the number of newly discovered breast cancers between the investigated periods, and the reason could be the sufficient "openness" of the health system for oncology patients during the period of the COVID-19 pandemic in Croatia.