Two seroprevalence studies of viral hepatitis A and hepatitis E were conducted in El Paso, Tex, and Cd Juárez, Mexico. Subjects were randomly selected, low-income pregnant women. Blood from 557 women in El Paso and 307 women in Cd Juárez, obtained from routine prenatal testing, was analyzed for antibodies to hepatitis A and hepatitis E. Women from both cities showed high seroprevalence rates of hepatitis A (75.8% in El Paso and 96.1% in Cd Juárez). Rates increased significantly by age, with 100% of women in Cd Juárez older than 28 years testing positive. Nationality and ethnicity were significantly associated with hepatitis A seroprevalence: Mexican nationals, 96.1%; US Hispanics, 78.8%; and US Caucasians, 36.4% (P < .001). With respect to hepatitis E, 0.4% of women in El Paso and 1.6% of women in Cd Juárez tested positive for anti-HEV. The rate of hepatitis A seroprevalence was higher for women with lower educational levels and for women residing in crowded households, but these findings were not statistically significant.