The aim of this study was to analyze the influence of farm conditions and season of birth on body mass, respiratory system diseases and diarrhea occurrence, and mortality during the first month of calves? life. The study was conducted on two tie-stall-system farms with intensive milk production and similar nutrition of dairy cows, but with differences in rearing conditions of calves in the first week of life. The calves were tied on lying area with straw as bedding material (farm A) or free in individual boxes with straw bedding (farm B). In the first consumption, they take 1-2 L of colostrum produced by their mother or by another cow (farm A), or 2.5-3 L of colostrum produced by their mother or by another cow or frozen colostrum (farm B). According to the results, average body mass of calves was significantly higher on farm B than of those on farm A at all ages (on birth, at 8 days, and 30 days). Mortality rate and diarrhea occurrence in calves were higher on farm B, while respiratory system diseases incidence was higher on farm A. All observed welfare indicators were very significantly (P < 0.01) influenced by farm conditions and birth season.