Our laboratory serves a 450-bed acute care hospital in the rapidly growing Gold Coast region. The problem facing the department comprised an almost 10 per cent yearly increase in patient numbers in the face of budgetary constraints and pressure to increase efficiency. In January and February 1992 a vigorous effort was made to reduce pathology test numbers without compromising quality of patient care. The approach adopted involved targeting 'unnecessary' tests, defined as those investigations that would not affect a clinician's management of the patient. A team effort by laboratory scientific staff and heads of clinical departments was aimed at scrutinizing the ordering patterns of junior medical staff, who generate most of the test requests. The result was a 'test per patient' figure of 8.2 for both months, calculated as the number of tests on each request form received. In comparison, for January and February of the preceding four years, 1988 to 1991, the number of tests per patient fluctuated between 9.9 and 11.8. Patterns of unnecessary ordering that emerged included duplicate ordering of identical tests due to poor communication between house-staff, too frequent repeats of tests (for example, daily liver function tests), crossmatch where low transfusion likelihood would make group-and-hold appropriate, tests generated by nursing staff, and numerous others where the result would not affect management (or indeed even be looked at!). The nearly 20 per cent drop in tests does not include those instances where all tests on a request form were disallowed and the encounter therefore not included as a 'patient' statistic.(ABSTRACT TRUNCATED AT 250 WORDS)