This study examined inequalities in infant mortality in Denmark in relation to maternal educational level, and compared the inequalities to those observed in a similar study 10 years earlier. It was a register-based study of all singleton births in Denmark 1991-92, a study population of 113,814 births. When adjusted for mother's age, parity, and smoking, the stillbirth rate was independent of mother's educational level, but a clear social gradient in infant mortality was observed. Compared with a similar study in 1982-83, infant mortality has decreased most in the highest educational group and has increased in the lowest educational group. In conclusion, social inequality in infant mortality in Denmark is pronounced and cannot be explained by differences in smoking habits. The social gap between different educational groups has widened during the last decade, but may partly be explained by the decreasing number of women in the lowest educational group.