A minicircle consisting of 1440 bp was isolated from male fertile sugar beet mitochondria. The entire nucleotide sequence of the minicircle was determined. There are several stop codons in all three reading frames and it is therefore unlikely that the minicircle codes for a polypeptide product. However, the minicircle is transcribed yielding a major RNA product consisting of 850 bases in addition to two very minor RNA products of 1100 and 950 bases, respectively. All three RNA products are transcribed from the same strand. The starting point for transcription of the major RNA product was determined by S1 nuclease protection analysis.