Background: Mumps is a viral disease primarily transmitted by infected individuals. A milestone in controlling mumps in Poland was the introduction of mandatory MMR vaccination in 2003, protecting against measles, mumps, and rubella. Since then, the incidence has decreased substantially, and complications have become rare. Objective: The aim of the study was to conduct an epidemiological assessment of the incidence of mumps in Poland in 2023 compared to previous years, taking into account the impact of the COVID-19 pandemic. Material and methods: The analysis of the epidemiological situation of swine fever in Poland in 2023 was conducted based on the interpretation of data from the nationwide epidemiological surveillance system. The percentage of those vaccinated with the first dose was determined based on data for the 2021 cohort (children aged 3 years), and the percentage of those vaccinated with two doses was determined based on data for the 2017 cohort (children aged 6 years). Vaccination effectiveness was estimated using the screening method. Results: In 2023, 966 cases of swine fever were registered in Poland. This represented a 4.8% increase in the number of cases compared to 2022, when 922 cases were reported. The overall incidence rate was 2.6 per 100,000 inhabitants, which was 5.3% higher than in 2022. The highest incidence rate, 3.6 per 100,000 inhabitants, was recorded in the Śląskie voivodeship, and the lowest, as in previous years, of 1.2 per 100,000 inhabitants in Dolnośląskie voivodeship. The highest incidence(13.7/100,000) was recorded in children aged 0-4 and 5-9 (17.3/100,000). The incidence in men (3.0/100,000) was higher than in women (2.1/100,000). In 2023, the number of hospitalisations due to mumps in Poland was 12, a decrease of 40% compared to 2022, when 20 people were hospitalized. Conclusions: In 2023, there was an increase in the number of registered cases of mumps, indicating a general upward trend. The decline in cases in2020-2021was the result of the COVID-19 pandemic, which was accompanied by restrictions significantly limiting the transmission of diseases spread by droplets, including mumps. Despite the increase in the number of cases in 2023, the level remains below that observed in the period before the COVID-19 pandemic.