Previous environmental surveys of eukaryotic diversity using the small subunit ribosomal RNA (SSU rRNA) gene have revealed many clone sequences that branch near the base of Fungi. In this work, we demonstrate that many of these sequences, including those of the environmental clade LKM11, form a monophyletic and strongly supported group that also includes two sequences derived from the parasitic genus Rozella. This novel clade, called here "Rozellida", is the deepest branch of true fungi so far identified, and appears to be extremely diverse in the environment.