This study indentifies the factors in the implementation of the Integrated Health Insurance (Seguro Integral de Salud - SIS) that are impeding the fully access of the poorest to the entitlement to a health scheme and the use of health services in Peru. The analysis emphasizes the differences in the effects of this process on female and male groups. The information collected is based on interviews with health personnel working under the SIS scheme and female and male inhabitants of six poor districts where SIS is being implemented. The results demonstrate that failures at the level of the patterns guiding the practice of health personnel in the implementation, the way of addressing people’s health needs and the management of SIS in the provision of resources to health centers are the reasons why SIS has not reduced, and in some cases has enhanced, the social and gender inequality among poor population, and in particular between women and men.