This book stresses primary infertility among women who showed endometria in proliferative phase and were not ovulating. In such cases, it is the histological immaturity which is responsible for infertility. Secretory phase endometrium means that the woman is ovulating. Defect may be either depletion of glycogen which may result in inadequate uterine bed at the time of implantation and hence, may be one of the causes of infertility. Glycogen shows a regular variation in endometrium during each menstrual cycle and is under the influence of oestrogen and progesterone. In primary infertility, glycogen deficiency occurs in secretory phase. This poor secretory activity might be responsible for laying down of unsuitable bed for ovum thus resulting in infertility. Abnormal glycogen distribution in glands and stroma of secretory phase endometrium may lead to poor preparation of the endometrium for nidation in infertility.