Abstract: The presented matK tree primarily agrees well with the previously presented rbcL tree and combined rbcL +atpB + 18SrDNA tree. According to the matK tree, the monocotyledons are monophyletic with 100 % bootstrap support. Acorus diverges first from all other monocotyledons (90 % bootstrap support) in which two major clades are recognized: one (89 %) consisting of Alismatanae and Tofieldia (Nartheciaceae), and the other (< 50 %) comprising Lilianae, Commelinanae and Nartheciaceae other than Tofieldia. Within the latter major clade, Petrosavia and Japonolirion (Nartheciaceae) (82 %) diverge first from the remaining taxa (< 50 %) in which two clades are formed: one (81 %) consisting of Pandanales, Dioscoreales and Nartheciaceae-Narthecioideae, and the other (< 50 %) comprising Liliales, Asparagales and Commelinanae. In the former clade, Dioscoreales and Narthecioideae are grouped together (88 %). In the latter clade, Asparagales and Commelinanae are grouped together (< 50 %). Differences between the matK and rbcL tree topologies appear in the positions of Tricyrtis (Calochortaceae) and Dracaenaceae. Differences between the matK and combined rbcL +atpB + 18SrDNA tree topologies exist in the positions of the Petrosavia-Japonolirion pair (Nartheciaceae) and Pandanales. The stop codon position of the matK gene appears to be highly variable among the monocotyledons, especially in the Liliales.