The objective of this study was to examine the association between social class of the head of household at the time of birth and mortality and morbidity during the first 10 years of life in a cohort of all 117 212 children born to women who both lived, and delivered in hospital, in Oxfordshire or West Berkshire during the period 1 January 1979 to 31 December 1988. Logistic regression was used to estimate social class gradients, with odds ratios (OR), for mortality during the early neonatal period, late neonatal period, post-neonatal period, post-infancy period and throughout the first 10 years of life. Logistic regression was also used to estimate social class gradients, with ORs, for hospital admission rates for 16 broad groups of diseases during years 0-3, 4-6, 7-10 and throughout the first 10 years of life. Poisson regression was used to estimate social class gradients, with effect sizes, for overall hospital admission rates during years 0-3, 4-6, 7-10 and throughout the first 10 years of life. The study revealed a significant social class gradient in mortality during the first 10 years of life (adjusted OR for each decrement in social class category 1.08; [95% confidence interval 1.03, 1.14]). The study also revealed a significant adjusted social class gradient in hospital admission rates for 14 of the 16 groups of diseases during the first 10 years of life. For the majority of these, the social class gradients had attenuated somewhat by the later childhood years. However, the social class gradient persisted throughout the first 10 years of life for diseases of the respiratory system (1.07 [1.05, 1.08]), diseases of the digestive system (1.06 [1.04, 1.09]), and injury and poisoning (1.07 [1.06, 1.09]). In addition, a significant adjusted social class gradient was found in overall hospital admission rates for each age group studied. This study suggests that there are significant social class inequalities in a wide range of adverse child health outcomes.