Phylogenetic relationships of the basidiomycete Lentinus were investigated using 20 morphological and 133 nucleic acid sequence characters from three regions in the 5' half of the nuclear-encoded large subunit rRNA. Molecular data were obtained from 34 individuals that represent 11 species in Lentinus, nine in the Polyporaceae, eight in the Tricholomataceae, and one in the Corticiaceae. Thanetephorus cucumeris (Tulasnellales) was used as an outgroup for rooting purposes. Most of the sequence variation was in regions that correspond to eukaryote-specific divergent domains D1 and D2. Molecular data alone yielded a well-resolved cladogram but morphological data alone were insufficient to resolve phylogenetic relationships. The most resolved cladograms were obtained with a combined analysis of molecular and morphological characters. Bootstrap and decay index measures of branch robustness had a significant positive correlation, but some branches with high bootstrap values were contradicted by near-minimal trees. Monophyly of Lentinus sensu Pegler was not supported. Rather, three monophyletic groups of Lentinus species were resolved. These largely correspond to Neolentinus, Panus, and Lentinus s. str. The latter appears to be derived from the Polyporaceae, suggesting that lamellae are products of convergent evolution.