Aim. The aim of the study was to determine the relationship between the mode of delivery and the course of lactation in primiparas in early postpartum period. Material and methods. The research was conducted amongst 200 primiparas including 100 after vaginal delivery and 100 after cesarean section. The study was conducted with the method of diagnostic survey with the author’s original questionnaire as a research tool. Results. The women after vaginal delivery initiate breastfeeding earlier and more often find it successful (p < 0.001). Almost all the primiparas after cesarean delivery formula-fed their newborns (p < 0.001) and they started supplementary formula feeding earlier in comparison to women who had vaginal delivery (p < 0.001). Problem-free breastfeeding was declared by 15% of the respondents after vaginal delivery and 4% of those who had a cesarean section. Conclusions. The mode of delivery influences the lactation process. The primiparas after cesarean delivery had problems with breastfeeding more often than those after vaginal birth.