A Rapid Approximate Intelligence Test consisting of a series of mathematical computations is described. This test has been standardized against the WAIS. The main conclusions which may be inferred from its use are outlined. The advantages of the test are brevity, as it can be administered in two or three minutes, and the fact that no equipment is necessary.However, the RAIT has the disadvantage of testing only one aspect of intelligence, namely, arithmetical ability, an area of intelligence susceptible to impairment in psychiatric illness. The use of more comprehensive brief intelligence tests, e.g., the Kent EGY Test(1), probably gives more insight into the intellectual capacities of psychiatric patients. Nevertheless, the RAIT would appear to be an excellent instrument to add to the clinical armamentarium of the busy psychiatrist who has no immediate access to facilities for more sophisticated intelligence testing.