Vaccination is method used to protect against several disease. Therefore, mother must take care to vaccinate their children to protect them from these disease. The aim of this study was to assess mother’s knowledge of vaccination with children under the age five at Goz nafisa clinic, Omdurman, Khartoum stat, Sudan, during the period from march to may. The study included the “100”sample of mothers who attended the clinic during that period and then collected the data using questionnaire designed for study purposes. And then the analysis of the data using statistical package for social sciences. The result of the study showed that the age group from 30__40 ‘and their level of education was respectively 54%, 61%, of the study sample. The study showed that the mother with knowledge of the time of vaccination and types of vaccine, and knowledge of the symptom that occur after vaccination, and those who agree that vaccination protects against the incidence of disease were their proportion respectively 51%, 96%, 99% of the study sample. Also explained that mother who have knowledge of benefits of the vaccination, and the cases that not vaccine the child, and cases in which the child is vaccinated against measles at the age 6 month was respectively 79%, 80%, 12%. The study found that mothers had a moderate knowledge of vaccination time and type and good knowledge about complication can occur after vaccination. The study recommended establishing continuous health education program of all mother in the village.