Wetland forest communities are seriously reduced and degraded throughout most of Europe, but significant areas still survive in the east and north-east. Data from 91 forest structures that support biodiversity are analysed in 369 relevés of Latvian wetland forests. These structures include variations in topography, stand composition, water movement and dead wood features occurring in semi-natural conditions undisturbed by management. There is clear structural differentiation between coniferous and deciduous wetlands. The study supports the widely held views on European forest quality: low volume of high-diameter (>50 cm) snags and logs, too few overmature trees, and the threat to pattern heterogeneity caused by traditional forestry and silviculture. Twenty areas (totalling c. 3800 ha) are identified as reserves that should be strictly protected in Latvia in order to maintain representative and intact samples of wet forest belonging to Eurosiberian alder swamps (Alnetea glutinosae), broad-leaved forests (Querco-Fagetea) and boreal forest (Vaccinio-Piceetea) communities. Based on habitat features and site ecology, the concept of sustainable forestry must be incorporated widely in utilization of European wetland forests in order to prevent further loss of biodiversity.