The aim of this study was to assess the impact of asymptomatic infections of mink with Aleutian mink disease virus (AMD on reproductive performance and the morphology of the internal organs. The study drew its subjects from two farms where the disease was endemic and included 450 clinically healthy female mink divided into three equal groups: two AMD positive groups and one AMD negative control group. The mink were subjected to clinical observations throughout the period of reproduction, and then for the first seven weeks after birth. Data collected during this period were evaluated using selected breeding and reproductive indices. All reproductive indices including conception rate, litter size, and litter weight at birth as well as neonatal mortality were substantially poorer. Histopathological examination revealed changes typical for AMD, particularly in the spleen, kidneys, liver, and lymph nodes. The results highlighted and proved the frequently underestimated extent of economic losses on farms where AMD is endemic yet the mink stock is apparently healthy.