It has been stated that health care reform and extension of an appropriate primary health care system will reduce the overutilization of the hospital emergency services (HES). The objectives of this study were to confirm whether the observance of the preventative programmes established in the primary health center (PHC) and/or social risk factors are related to the frequency of utilization of the HES. The results of a questionnaire of 304 emergencies (276 children) from our PHC that attended the HES between June and December of 1991 were analyzed. The sample was divided into three groups depending on the level of frequency of the children to the HES during the year. The information obtained from the clinical records from the PHC enabled us to assess the family social risk, as well as the follow-up of the preventative programmes established in the PHC of this population. No significant differences were found between the frequency of the child's visits to the HES and the degree of follow-up in the PHC. There was a relationship between the frequency to the HES and frequency to the PHC (p < 0.001). The higher the social risk of the children, the higher the frequency to the HES, although the difference was not significant. Correct follow-up of the preventive programmes established in the PHC does not diminish the frequency of visits to the HES. Social risk factors, as well as anxious characteristics of the child's family, should be considered when facing the problem of overutilization of the HES.