Client satisfaction is a relevant aspect for assessing the efficiency of a Medical Advisory Board. The study presented here aimed at determining the factors that guarantee satisfaction. These findings are essential for the further development of the service of the Advisory Board of the City of Vienna for Environmental Medicine ("UMB"). To this end a brief anonymous questionnaire was sent to 245 clients. This comprised elements evaluating the degree of satisfaction with the consultant service of the Advisory Board, fulfillment rate of expectations, solutions offered for various problems, and whether--if necessary--the "UMB" Advisory Board would be consulted again. A satisfactory response rate of 43% was obtained. The results show a high degree of satisfaction among the clients with the consultations (= 78%) despite unresolved or only partly resolved problems (71%) and questions that remained open for discussion (38%). Approximately 90% of the clients would again consult "UMB" for advice. The reasons for consultation did not show any significant influence on the client satisfaction. However, satisfaction of clients depended on whether or not a solution was found in respect of their problem and on the action taken by "UMB" to solve it. Summarising the findings, the analyses show that apart from on-the-spot assessment and detailed inspection, comprehensive case histories and interviews are an important basis for further clarification of problems caused by environmental factors.