['We aimed to ascertain the efficacy of an intervention in which laboratory test costs were provided to clinicians as a pocket-sized brochure, in reducing laboratory test costs over a 4-month period.', 'This was a non-randomised intervention study in the Internal Medicine wards at Steve Biko Academic Hospital, Pretoria, in which the intervention was laboratory test costs provided to clinicians as a pocket-sized brochure. The intervention period was the winter months of May - August 2008 and the pre-intervention period was the same months of the preceding year. In the two 4-month periods (2007 and 2008), the number of days in hospital and the laboratory tests ordered were computed for each patient admitted. For the intervention and control groups, pre- and post-intervention cost and days in hospital were estimated.', 'The mean cost per patient admitted in the intervention group decreased from R2 864.09 to R2 097.47 - a 27% reduction. The mean cost per day in the intervention group as a whole also decreased, from R442.90 to R284.14 - a 36% reduction.'] Does providing clinicians with information on laboratory test costs lead to reduction in hospital expenditure?