The aim of this survey was to study the requests written for hepatitis B virus (HBV) serology tests to ascertain their compliance with French prescription guidelines; additional costs incurred by inappropriate requests were also determined, as was the appropriateness of the physicians' interpretation of the test results. This was a cross-sectional practice inquiry involving 118 prescriptions for HBV serology tests. Data were prospectively collected in June 2005 from laboratory heads and prescribing physicians. The prescriptions were written for 188 patients (64% women), aged 35 years on average, mostly by general practitioners (65%) and gynecologists (25%). Prescribing physicians reported the following clinical situations as their main reasons for ordering HBV serology tests: pregnancy (25%); vaccination (20%); acute hepatitis (18%) and screening a patient with a risk factor (19%). Failure to comply with current guidelines was noted in 74% of the prescriptions and vague wording in 45%. The additional cost due to ordering inappropriate serology tests was 43.41 euro per prescription. The physician's interpretation of the test results was considered excellent (27%), fair (59%) or false (14%). Guidelines for the prescribing of hepatitis B serology tests need to be more rigorously applied in daily clinical practice. City hospital networks should promote further in-service training for physicians.