The GAO review of 122 Federal agencies authorized to implement drug testing programs as of September 1990 found that 40 reported conducting drug tests. Of the 122 agencies, 68 designated 10 percent or fewer of their employees as being subject to random drug testing because they were in testing designated positions (TDP's). In all Federal agencies, 463,974 employees were in positions designated as TDP's. The extent to which TDP employees underwent testing varied. Some agencies planned to test as few as 4 percent of their TDP's annually, while others planned to test as many as 200 percent. Budget estimates of drug testing program costs totaled $11.3 million for fiscal year 1991. The 40 agencies reporting they conducted drug tests had performed 31,259 tests for the 6-month period ending September 1990 and found illegal drugs present in 169 cases (0.5 percent). Appendixes contain an overview of Federal agency drug testing program, drug testing results for the 6-month period ending September 1990, and detailed information on nine Federal agencies visited by the GAO. 17 tables and 2 figures