This study was designed to compare changes in performance on selected measures from the Halstead-Reitan neuropsychological test battery over a 5 to 6 year interval for normotensive and medically treated, uncomplicated essential hypertensive adults. Mean performance level was poorer for hypertensive than for normotensive groups on an average impairment index and a number of the individual impairment rating scores, but no Time of measurement X Blood pressure interactions were observed. There was no evidence of improvement or decline for normotensive or hypertensive adults and no evidence suggesting that the hypertensive group could be characterized as "cognitively impaired" in an absolute or clinical sense.