The epidemiology of inflammatory bowel disease (IBD) in Poland has been recognized to only a limited extent. We aimed to estimate the prevalence and incidence of IBD by analyzing data from the National Health Fund, Poland's sole public health insurer. Administrative health claims collected over the 2009-2020 period were used to identify patients with Crohn's disease (CD) or ulcerative colitis (UC). A definition of a case comprised at least 2 records assigned K50 or K51 codes, plus at least 2 prescriptions for IBD drugs reimbursed, or else intestinal surgery preceding the record. The crude and European age‑ standardized rates (EASR) and 95% CIs were calculated for prevalence and incidence. Time trends were also analyzed. As of 2020, there were 23 574 patients with CD and 73 235 with UC. The CD and UC prevalence was respectively 61.6 (EASR 60.3) and 191.4 (EASR 187.85) per 100 000. The prevalence of CD and UC was higher in men (64.1; EASR 61.3 and 201.4; EASR 202.7, respectively) than in women (59.3; EASR 58.4 and 182.0; EASR 175.5, respectively). The incidence of CD was 4.7 per 100 000 (EASR 4.6), and that of UC 12.5 (EASR 12.3). Through the period 2012-2018, the prevalence of both conditions was rising, even though downward trends were noted for the disease incidence. The prevalence and incidence of IBD in Poland are presented, with time trends showing a substantial increase in the disease burden over the years 2009-2020.