BACKGROUND The World Health Organization has declared COVID-19 a global pandemic. This paper presents an epidemiological analysis of the first phase of the COVID-19 epidemic in Poland. MATERIAL AND METHODS This cross-sectional study was carried out between 3 and 27 March 2020 on a sample of 1389 laboratory-confirmed COVID-19 cases in Poland. Data were obtained from epidemiological reports collected by the Chief Sanitary Inspectorate. Analysis includes the number of COVID-19 cases, number of deaths, number of hospitalizations, number of people quarantined, and number of laboratory tests performed. RESULTS The first case was confirmed on 4 March 2020. Over 24 days after the first case, the total number of confirmed infections rose to 1389 (34,000 laboratory tests were performed). The highest incidence rates (over 5 per 100,000) were observed in the 2 central administrative regions (Mazowieckie and Łódzkie) and in the south-western region of Dolnośląskie, which borders the Czech Republic and Germany. Based on available data about age and sex, a clearly higher incidence was observed in the 20-29 years (4.0 per 100,000), 40-49 years (4.1 per 100,000), and 50-59 years (4.3 per 100,000) age groups. In the period analyzed (24 days), there were 16 confirmed deaths (average age 65.5 years; 81.2% males). CONCLUSIONS The proportion of women and men with confirmed COVID-19 infection was similar to the sex ratio in the general population. Infections were relatively less common in those aged under 20 years. The largest numbers of confirmed cases were detected in 3 of the 4 largest cities, each of which has an international airport.