The Kenya government in collaboration with other stakeholders involved in the provision of family planning services have put in place various strategies and policies to increase uptake of family planning services. These are aimed at increasing contraceptive prevalence rate (CPR), reduction in both total fertility rate (TFR) and unmet need for family planning services. Despite the various strategies and policies, total fertility rate still remains high at 4.6 percent, while CPR and unmet need for family planning are estimated at 46 percent and 24 percent, respectively. The purpose of the study was to examine the utilization level of family planning services and to analyze the determinants of demand for family planning services among women in City slums in Kenya. To realize this objective, a survey design was adopted. The target population constituted women in city slums in Kenya, who were identified through multistage random sampling. Primary data was collected from the women using a structured interview schedule. A fact sheet was used to summarize the data collected before it was cleaned, coded and edited for completeness and accuracy. The study revealed low usage of contraceptives compared to the national level. Use of the services varied in terms of demographic and socioeconomic factors of the woman and also the woman’s perception in terms of the facility/provider factors such quality, friendliness of staff and promotion. Various factors accounted for the low use of family planning services. These included partner’s approval, quality of the services, friendliness of the staff administering the services and the woman’s knowledge about family planning services. Other factors included the woman’s income level, proximity to the provider and the religious background of the woman. To increase the use of family planning services among women in slums, activities of community based distributors should be revived and enhanced, promotion of family planning education and activities at the household level should be accorded priority. Formation of lobby groups to enhance cultural change, awareness creation and counselling and integrating family planning services with HIV/AIDS are recommended.