This  study  investigated  the biochemical  and  hematological  parameters  (at the beginning, after 90 days, and at the end of the experiment) of the pure genotype Black Slavonian (BS) pigs and crossbreeds of Black Slavonian and Duroc (BSxD) pigs, fed the same diet and kept under the same extensive free-range  conditions during 200 days of the experiment. In the study, BS and BSxD pigs showed differen- ces in blood protein levels, hinting at dietary disparities. Glucose and triglyceride levels differed between the two groups, affecting energy availability and fat depo- sition. BS pigs showed higher white blood cell counts, while BSxD pigs exhibited more rapid metabolic activity. Alkaline phosphatase activity declined over time, with variations between  the groups. Phosphorus and magnesium concentrations decrea- sed with pig growth, reflecting changes in metabolic demands. Hemoglobin, hema- tocrit, and red blood cell counts varied between the groups. MCV and MCH values in BSxD pigs indicated rapid red blood cell production. Platelet counts fluctuated with age. This study offers insights into the influence of genetic characteristics and growth rates impact biochemical and hematological parameters of pigs kept under free-range conditions, aiding swine population management.