The aim of the study is to determine the scale of interregional migrating patients' hospitalizations in Poland in 2013-2017, as well as their demographic and medical factors, total costs and time changes.Data from the NHF (National Health Fund) regarding hospitalizations in a given province of patients registered in another province in Poland in 2013-2017 were statistically analyzed. Times series analyses as well as coefficients of correlation, determination and variation were used.The number of patients hospitalized outside their regional registration and the cost of their hospitalization increased from year-to-year during 2013-2017. There was a large variation in provinces in terms of inflow of patients and costs of their hospitalization, while there was only a small variation in terms of outflow of patients and costs of their hospitalization in the analyzed years. Among the patients hospitalized outside the province where they were registered, there were more women then men, while the age group was dominated by 60-year-olds and their share in the subsequent years increased, while the share of other age groups remained unchanged or decreased. The most and increasingly more from year-to-year hospitalizations outside the regional registration were due to neoplasms and diseases of the circulatory system.The results of the study may significantly contribute to the proper planning of securing the health needs of the inhabitants of particular regions, and to improving the quality and economic efficiency of health services in individual NHF branches.