On the basis of the thesis that social inequality has increased during the nineties in all western societies, and that this development is a reason for considerable concern with respect to public health, the authors propose the establishment of a long term monitoring system within the Swiss school health services. A re-analysis of the data obtained in a Swiss epidemiological study of seven-year-olds in the eighties demonstrates that social class was an important determinant of health and development of these children also during a period of economic boom. For various health and developmental problems odds-ratios (lower class vs. upper class) between 1.7 and 6.4 were found. Social class of the parents is considered as a reliable indicator of the socio-economic situation of children also for future long term observations. The number of significant somatic health problems as well as disorders of motor and speech development of six- or seven-year-olds are proposed as indicators of health status which can be assessed repeatedly at reasonable cost and with standardised methodology. This project could be started rather easily within the newly established Swiss "Health Observatory".