Anemia is one of the common medical conditions in pregnancy. The World Health Organization (WHO) describes anemia in pregnancy as hemoglobin levels less than 11.0 g/dl. According to the 2008 report of WHO, 1.62 billion (24.8%) people are affected globally from anemia. This situation is more serious in developing countries where around 60% of the pregnant women are anemic. Objective of the study was to determine the prevalence of anemia in pregnancy at the Liaquat National Hospital, Karachi, a tertiary care center. A Hospital based study was designed, where women delivered at the Liaquat National Hospital, Karachi between the periods June 2012 to June 2013 were enrolled in this study. Hemoglobin was assessed for all pregnant women categorized as anemic on the basis of severity. Data was gathered with regard to their antenatal progress and factors influencing anemia in pregnancy. Descriptive statistics was done and the Chi square test was performed to examine the relationship between outcome variables (anemic/noanemic) and other independent variables. One hundred and twenty (24%) pregnant women were found anemic. Among these seventy two were mild anemic (60%), while thirty percent (36) were moderately anemic and remaining twelve (10%) were severely anemic. Seventy seven percent was identified to have iron deficiency anemia. Anemia was significantly related with lower age group (18 - 29 years), low income, greater family size, underweight and previous history of anemia. The study showed that iron deficiency anemia is the most common cause of anemia in pregnancy and is a chief public health issue in developing countries.