Résumé : Background: Much attention has focused on variations in therapeutic strategies across catchment areas and the related question of whether the differences in attitudes are due to socio-economic variables in the studied population or to physician uncertainty about making a specific therapeutic recommendation. Subjects and method: We monitored the emergency admission rate for patients with alcohol or opiate related problems of 9 resident psychiatrists for a year. To rule out differences in population characteristics, the study took place in only one hospital: Brugmann University Hospital, whose catchment area is the north of Brussels. Results: Our results show 3 distinctive practice styles. We suggest that variation in urgent admission rates for patients with alcohol and opiate related problems can be due not only to the socio-economic variables of the population, but also to medical uncertainty about the effectiveness of admission for the treatment of these disorders. Conclusion: The extent of uncertainty about appropriate standards of care and the plausible related inappropriate care and welfare losses are discussed.