The taxonomic position and properties of an unidentified fungus isolated from wheat roots was investigated. The Sterile Red Fungus (SRF) is characterised by its fast growing habit, red pigmentation, non-sporing nature and mycelial form resembling some Laetisaria and Limonomyces species. rDNA variation was used to study the relationship of the SRF to Laetisaria spp. and Limonomyces spp. Nucleotide sequence obtained from eight Laetisaria and three Limonomyces species representing the ITS 1 region, were analysed by PCR and direct sequencing. Plant growth promoting properties of the five taxa were also determined. The SRF had closest identity (98%) to British material of Limonomyces roseipellis. UPGMA analysis of ITS 1 DNA sequence support a close relationship between SRF and L. roseipellis. The relationship inferred by nucleotide sequence data was supported by phenotypic analysis; both L. roseipellis and the SRF were shown to promote the growth of wheat plants. Unexpectedly, Laetisaria arvalis and material named as Limonomyces roseipellis from New Zealand appeared to be closely related with 98% rDNA sequence identity, suggesting the misidentification of the New Zealand collection.