Objective: To examine the concurrent validity of a newly developed telephone adaptation of the Modified Mini-Mental State Exam. Background: Longitudinal studies of cognition may be advantaged by availability of assessment instruments that can be used over the telephone, as well as in person. Method: Subjects were 263 noninstitutionalized elderly residents of a rural community in southern Idaho, aged 65 to 93, who had little or no cognitive difficulty. At an average interval of four weeks, we administered the Modified Mini-Mental State Exam (3MS) and the newly adapted Telephone Modified Mini-Mental State Exam (T3MS). Order of administration was randomly assigned. Results: Agreement between scores on the two instruments was good (r = 0.82, p < 0.001). When we applied various cutoff scores to the instruments, thereby generating assignments of individuals to "screen positive" and "screen negative" groups, the percent agreement in screening results ranged from 80% to 96% as we reduced the cutoff scores from 90 to 74 (100 points possible). Conclusions: At least among subjects without major cognitive syndromes, the Telephone Modified Mini-Mental State Exam provides a reasonable substitute for the more costly in-person 3MS. The telephone instrument should now be tested over a broader range of cognitive abilities in order to assess its validity in more impaired subjects, e.g., by studying an institutionalized sample.