Order unanimously reversed on the law without costs, motion denied, petition reinstated and matter remitted to Supreme Court for further proceedings on the petition. Memorandum: Supreme Court erred in dismissing the petition, seeking review of an order of retention, as untimely. The time within which to commence a review proceeding begins to run on the date that the allegedly ill person is served with the order of retention (see, Matter of Coates, 9 N.Y.2d 242, 252, appeal dismissed sub nom. Coates v Walters, 368 U.S. 34). Petitioner was served with that order on May 27, 1994; thus, her petition, filed on June 17, 1994, is timely (see, Mental Hygiene Law § 9.35). Although the order of retention has expired, we decline to treat the issue as moot. Because orders of retention are of short duration, it is likely that this issue would otherwise evade appellate review (see, Matter of Hearst Corp. v Clyne, 50 N.Y.2d 707, 714-715).