Different fragments of the maxicircle of the kinetoplast DNA (kpDNA) from Crithidia oncopelti were cloned (Fig. 1, 2) and tested for ARS-activity (ARS, autonomously replicating sequences). ARS-activity was expressed as number of transformed yeast cells per microgram plasmid DNA, as number of transformed cells per number of plasmid molecules (transformation efficiency, TE) and as number of transformed cells per kilobase pair of cloned kpDNA (specific transformation efficiency, TES) (Fig. 3, Table 1). All DNA fragments studied showed ARS-activity. Large fragments exhibited higher ARS-activities than their smaller subfragments. The number of fragments showing ARS activity and their distribution within the maxicircles (Fig. 4) suggest that there was no strong correlation between sites with ARS-activity and the replication origin of kpDNA.