A rapid population growth is a burden on the resources of many developing countries. Unregulated fertility, which contributes to such situations, compromises the economic development and political stability of these countries. Contraceptive use is the lowest in Yemen where about 1 out of 5 married women of reproductive age use contraception. The study conducted to evaluate the impact of implementing an educational program of family planning upon Yemeni women at Sana'a City. Quasi-experimental research design was used. It was conducted in Al-Sabeen Hospital and Al-Olofi Center which included a sample of one hundred and forty women, divided equally into two groups: study group and control group (seventy for each group). The tool was used; contain sociodemographic data and women' knowledge about family planning. The main result of the present study, more than half of the control group (57.1%) their age was between 30 years and less than 40 years and (40%) of studied group and (45.7 %) of the control group had preparatory education. The number of pregnancies was (41.4%) of the study group and (58.6%) for the control group had three or more times. Unwanted pregnancy represented (64.3% and 57.1% respectively) of both study and control group. Also women' knowledge had a poor score on pretest, improved to good score on immediate post test, and remaining good score with slight decrease on follow up test with highly statistically significant difference. The study recommended that FP program should involve men as well as women, and ensure all primary health care clinics provide counseling on FP.