The measured ozone profile is often not a smooth curve with a maximum in the stratosphere. It exhibits narrow layers of enhanced ozone concentration (positive laminae) and of depleted ozone (negative laminae). Here we deal with the trends in ozone laminae characteristics. All sufficiently long data series of ozonesonde soundings from the Northern Hemisphere poleward of 30¿N are analyzed separately for Europe, northern America, Japan, and the Arctic. The trends in ozone laminae are quite strong, much stronger than those in total ozone at middle latitudes. A reversal in trends in the ozone laminae characteristics, mainly in the overall ozone content (deficit) in positive (negative) laminae per profile and the number of laminae per profile, is found to have occurred in the mid-1990s. Whereas a negative trend was observed before the mid-1990s, a positive trend was observed after about 1995. We assume this change in the ozone laminae trend to be caused predominantly by a change in the trends in circulation in the middle atmosphere.