In-depth understanding of women’s nutritional status is crucial to reducing maternal mortality and food insecurity. The percentage undernourished is higher in Ethiopia than in any other sub-Saharan African country. Thus this study focuses on undernutrition in Ethiopia to assess levels and socio-demographic differentials between rural and urban areas, and to analyze determinants. The paper uses the 2000 and 2005 Ethiopian Demographic and Health Surveys (EDHS), comprising 13,057and 5,677 non-pregnant and non-postpartum women age 15-49, respectively. Women’s body mass index (BMI) (kg/m2) is used as a measure of women’s nutritional status, and those with a BMI value less than 18.5 are considered to be at risk of chronic energy deficiency (CED). A logistic regression model was employed to identify important determinant factors of women’s undernutrition. The study finds that 30.5% of women in the 2000 EDHS and 26.9% of the women in the 2005 survey were undernourished, of whom in the 2000 survey 19.4% were moderately undernourished and 11.1% were severely undernourished. Similarly, in the 2005 survey 18.0% were moderately undernourished and 8.9% severely undernourished. The levels of undernutrition were almost 1.5 times higher for rural than urban women. There seems to be some improvement in women’s undernutrition status between 2000 and 2005.