Reports that the presence of persistent organic pollutants in fat may affect fatty acid metabolism prompted this research aiming to study the relationship between the contents of γ-HCH and DDT, DDE, DDD, and ΣDDT, and fatty acid composition of milk fat. The material consisted of 50 samples of cow and mare milk, collected in 2015. Ludwicki’s and the Röse-Gottlieb and IDF Standard methods were used to prepare the samples. Statistical analyses were conducted using Statistica 12.0. There was a negative correlation between the content of γ-HCH and C16:1, C17:1, C18:1c9, C18:1c9c12, and ΣMUFA in cow milk fat and C13:0, C14:0, and C10:1 in mare milk fat. A positive correlation was observed between γ-HCH and C6:0 to C12:0, C14:0, C18:1t16, and ΣSFA in cow milk fat, and between this compound and C14:0iso, C16:1, C17:1, C18:1c9,11, and ΣMUFA in mare milk fat. A negative correlation between the contents of ΣDDT and C16:1, C17:1, C18:1c9,11,13 and ΣMUFA in cow milk fat and C16:0iso, C17:0, and C18:3 in mare milk fat was noted. A positive correlation was found between the contents of ΣDDT and saturated and polyunsaturated fatty acids and ΣSFA and ΣPUFA in cow milk fat, and C18:2c9c12 in mare milk fat. The correlation between the content of selected organochlorine compounds and the composition of fatty acids in cow and mare milk fat indicates the strong influence of these environmental pollutants on the nutritional value of milk fat.