Mitochondrial DNA has been isolated from Trimorphomyces papilionaceus. By analyzing DNA fragments digested by restriction enzymes, a restriction site map has been constructured. The mtDNA of T. papilionaceus amounts to 48.5 kb in size and is circular in structure. Entire mitochondrial DNA was cloned in E coli plasmids and Northern blot hybridization was done using cloned and subcloned DNAs as probes. Based on hybridization results of mitochondrial RNA transcripts, a transcription map was prepared.