Procedures for the preliminary screening of asymptomatic adults who wish to exercise are reviewed with particular reference to experience gained through the mass use of the physical activity readiness questionnaire (PAR-Q) and the Canadian Home Fitness Test (CHFT). It is argued that both a brief submaximal exercise test and a subsequent moderate increase of habitual activity are extremely safe tactics to recommend to a symptom-free adult. There are some useful minor modifications which could be made to the PAR-Q instrument, but its sensitivity and specificity relative to such criteria as medical examination, hypertension, CHFT completion and exercise-induced ECG abnormalities compare favourably with alternative self-administered procedures. The basic difficulty of screening an asymptomatic population (highlighted by Bayes theorem) is the high percentage of false positive and false negative test results. One remedy would be to stratify the population in terms of known cardiac risk factors and to restrict detailed pre-exercise screening to the high risk segment of the population.