The paper presents the phenomenon of implantation. Discussed the mechanisms of its individual stages: apposition, adhesion and invasion. It explains the mechanisms of hormonal regulation and paracrine these phenomena. Attention is paid to the interaction of the embryo and the endometrium. The complexity and complexity of the mechanisms controlling the implantation mean that even a slight disturbance of homeostasis of the organism leads to a reduction of fertility. Apposition disorders associated with the possibility of ectopic pregnancy or placenta previa, abnormal adhesion to the lack of implantation, and thus the often elusive early miscarriage. In contrast, the invasion of endometrial abnormalities may be responsible for cases of adjacent or ingrown bearings, but also due to the induction of vascular lesions may predispose to hypertension and its complications.