The process of costing clinical biochemistry tests as a component of the commissioning of a unit management budgeting system based on an International Computers Limited (ICL) minicomputer system was examined. Methods of apportioning consumable and labour costs under direct and indirect cost headings and as test and request charges were investigated, and in this currently operational system it was found that 38% of consumable costs and 57% of labour costs were not a direct component of the routine analysis function. Means of assigning test costs to a given request source and the incorporation of such charges into clinical budget statements were looked at. A reduction in laboratory workload did not produce a comparable reduction in laboratory costs. For a theoretical reduction in workload of 20% only a 3.8% laboratory saving in recoverable costs could be expected.