BACKGROUND Economic crisis and sociopolitical instability are generally associated with worsening health and nutrition in developing countries. This study examines the role played by the attendance rate of young children at routine health activities in the deterioration of their nutritional status under adverse social and economic conditions. METHODS Two nutritional cross-sectional surveys were carried out in two districts of Brazzaville, capital city of The Congo, in 1993 and 1996. They included respectively 2807 and 1695 randomly selected children 4--23 months old. The children's nutritional status was assessed by height-for-age in z-scores. Using embedded general linear regression models, explanatory variables (routine health activities index, socio-demographic context, household economic level, prenatal factors) were tested as potential mediators for the effect of the year of survey on child mean height-for-age. RESULTS The routine health activities index declined sharply from 1993 to 1996. Its introduction in the regression model including all other explanatory variables led to a sharp decrease in the effect of the year on children's nutritional status, showing the important mediating effect of routine health activities. This result was encountered across all economic categories of households. Other explanatory variables showed more limited mediating effect. CONCLUSIONS Attendance at preventive health activities should be fostered in African urban communities facing harsh socioeconomic situations to prevent further deterioration in the nutritional status of children.