A yeast DNA sequence that behaves as a chromosomal replicator, ars1 (autonomously replicating sequence), has been isolated. On transformation, ars1 allows autonomous replication of all co-linear DNA. The replicator can integrate into other replication units and can function in multimeric form. The 850-base pair ars1 element has no detectable homology to other yeast sequences. Such replicator-containing plasmids can be used for the isolation of DNA sequences in yeast cells as well as for the study of chromosomal DNA replication.