Correspondence to:

The numbers of tests, imaging and diagnostic procedures ordered by doctors in primary care and hospital settings alike are rising. According to established guidelines, many of these tests may be unnecessary. Various non-clinical factors often underlie test ordering, and multiple prevalent problems associated with tests and their interpretation are often under-appreciated. These include the significant potential for cascades of further testing and patient harm. Multifaceted strategies may improve test-ordering beha-viour. Brief reconsideration of several points by the clinician before ordering the test is advisable. Doctors are all very fond of tests. Tests are very easy to order, they cost (us) nothing, the patient is impressed and pacified, and, until the test is scheduled, performed and interpreted, we win that most desirable of all commodities—time. Even if we are not too sure of what we are looking for, there is always the chance that the test will come up with something—at the very least, something, that can be followed-up by another test. With the growing number and escalating costs of modern tests, ‘‘the unbearable lightness of testing’ ’ constitutes an increasing burden on patients, doctors and society.1 Clinicians tend to disregard a number of problems associated with test ordering and with the interpretation of their results. This article discusses a few of those problems, not because they are new or unfamiliar, but because they are highly prevalent and rarely considered together, despite their significant impact on the costs and quality of healthcare. THE TEST IS REDUNDANT Test ordering is far from being a pure biomedical decision founded on a solid scientific rationale. The patient–doctor interaction is also a social interac-tion, and decisions about tests may be influenced by the doctor’s personality, the doctor’s emotional state, numerous patient characteristics (age, gen-der, look, status, insurance coverage), perceived patient pressure and other variables.