Objective: Unintended pregnancy is an important worldwide public health problem and one of the important factors contributing to high level of maternal and child morbidity and mortality. The study was aimed to assess the prevalence and associated factors of unintended pregnancy among pregnant women attending antenatal clinics.Methods: The study followed a descriptive cross-sectional design on 1,254 pregnant women who were chosen by convenient sample technique. The study was done at governmental hospitals in EL-Mansoura City, Egypt including: The antenatal clinics of Obstetric and Gynecological specialty Center at EL-Mansoura University Hospitals, Old General Hospital and Mansoura International Hospital. Two tools were utilized for data collection (The Urdu version of pregnancy intention scale (LMUP) and structured Interviewing Questionnaire.Results: The prevalence of unintended pregnancy among studied women was (29.1%), of which 229 (18.3%) were mistimed and 136 (10.8%) were unwanted. Age, higher family size, lower family income, gravidity, parity, increased number of children and birth spacing were significantly associated with unintended pregnancy.Conclusions: The study concluded that the prevalence of unintended pregnancy was high in El-Mansoura city. It is recommended to develop educational programs and campaigns especially for rural areas to improve awareness regarding family planning and other co-factors associated with unintended pregnancy.