PURPOSE: To evaluate the intraocular pressure washout time after discontinuing brimonidine 0.2% twice daily and latanoprost 0.005% once every evening. METHODS: We discontinued brimonidine or latanoprost in a masked fashion from primary open-angle glaucoma or ocular hypertensive patients. The intraocular pressure was measured twice weekly until patients returned to untreated baseline. RESULTS: In 32 patients, the mean longest eye washout time for brimonidine (n = 15) was 3.3 +/- 3.0 weeks and for latanoprost (n = 17) was 4.4 +/- 3.2 weeks (P = .24) In all but one patient, brimonidine returned to baseline by 5 weeks and latanoprost returned by 8 weeks. CONCLUSION: After discontinuing latanoprost or brimonidine, a wide variation exists in washout times among individuals, with latanoprost demonstrating a trend to a longer washout period, (Am J Ophthalmol 2001;131: 798-799. (C) 2001 by Elsevier Science Inc. All rights reserved.).