Physiological blood parameters help assess the health, feeding, immune, and reproductive status of wild animals. However, complicated sampling procedures make it difficult to establish the reference intervals for hematological parameters. Wild boar (Sus scrofa, Linnaeus 1758) is a popular game species. As a result, its population in Russia has been declining for the last decade. The wild boar is fertile and ecologically flexible; it responds well to biotechnical measures and have high population density. The research renders new data on the biology and physiology of wild boars. The blood samples were obtained from 68 juvenile and adult wild boars in the Kirov Region in 2017–2023. The body weight varied from 30 to 211 kg. Blood from the jugular vein was collected into anticoagulant test tubes. The laboratory tests involved a veterinary version of a MicroCC-20 Plus automatic analyzer (High Technology, USA). The stained smears were examined using a MEIJI TECHNO light microscope (Japan) under an immersion system with a ×100 lens. The red blood cell parameters were measured using the Vision Bio software (Epi, Austria). The research revealed the hematological profile of wild boars; the data were statistically processed, including, for the first time, the effect of sex and age on various hematological parameters. The significant differences (p < 0.05) between juvenile and adult females included the relative red cell distribution width by volume (standard deviation) and red blood cell thickness. The significant differences (p < 0.05) between juvenile and adult males were in hemoglobin, hematocrit, lymphocytes, and segmented neutrophils, as well as in such red blood cell parameters as total count, relative width by volume, area, perimeter, diameter, and sphericity index. The significant differences (p < 0.05) between juvenile females and males referred to hemoglobin and such parameters of red blood cells as total count, area, perimeter, and diameter. In adult males and females, it was the red blood cell thickness and platelet count. The research also yielded the lymphocytic profile of wild boar blood. The age affected such parameters as hematocrit (p = 0.02), segmented neutrophils (p = 0.00), and lymphocytes (p = 0.00). The body weight affected the hematocrit (p = 0.02) and mean red blood cell volume (p = 0.04). The differences in Sus scrofa hematological profile depended on the physiological status, diet, minerals, age, sex, and stress. The reference intervals may help interpret the hematological profiles of other wild boar populations and optimize the game resource management.