The use of rapid, on-site drug detection devices is reviewed. These tests permit the detection of various psychoactive substances in urine, and are easily used by nonskilled personnel. Saliva tests are available for detection of alcohol. These rapid tests have varying degrees of accuracy, and it is recommended that positive outcomes for all rapid tests be verified by standard laboratory procedures. The tests have potential use in the emergency room, doctor's office, drug treatment program, and the work place. When access to formal laboratory testing is limited by either time or location, an easily portable test can give critical information. A number of commercially available tests are reviewed for method, accuracy, advantages and disadvantages. Consequently, the interested practitioner should be able to find a suitable screening test from among the tests reviewed.