Gender and social class differences in illness among young people have been a neglected area in research on social inequities in health. It has been assumed that the illness differentials among adults persist throughout their lives. Only recently have social class health differentials among young people become a topic for research. The aim of this study is, first, to examine gender and social class differences in self-reported illness among young Finns; secondly, to determine whether the relationship between social class and limiting long-standing illness is similar among young men and women. In addition to the two main aims, we also examined whether several background variables have any impact on the relationship between class and illness or, directly, on illness. The data were derived from a nationwide Finnish 'Level of Living Survey', which was carried out by the Central Statistical Office of Finland in 1986. This interview material represents the noninstitutional Finnish population aged 15 years old or older. The number of respondents were 12,057, and the response rate was 87%. In the present study we only examined those who were 15-24-year-olds (N = 2238); i.e. 1101 men and 1137 women; the response rates were 91% and 92% respectively. Young women reported a limiting long-standing illness more often than young men. The prevalence of limiting long-standing illness increased with age. Cross-tabulation analyses showed virtually no relationship between social class and limiting long-standing illness. This held true irrespective of the various measures of social class that were used. Controlling the impact of several background variables in the logistic regression analyses did not alter this general result.