Measures of social class, if related to different class concepts, should differ in external consistency. External consistency depends on the character of the dependent variable. Two measures of social class are here used for independent variables, the socio-economic classification, the official index of Sweden, and a structural class concept. For dependent variables, ICD diagnose chapters, directly and in a simple grouping, are used on a material from health insurance authorities. Class inequality is measured both as to size and direction, by Gini-index and rank-order correlation, respectively. Separate analyses are made for the whole material, men and women, and doctor certified absence days. Results show clear differences between the class measures for diagnoses more closely associated to work conditions, while the measures coincide in other cases.