A repeated sequence, named RPS1, approximately 2 kb in size, is found mainly in chromosome 6, the second most variable chromosome among the eight chromosomes of Candida albicans. Most of the RPS1 units of chromosome 6 seem to be located within a single region of about 100 kb in strain FC18. In both strains FC18 and NUM812, a part of RPS1 is apparently tandemly repeated. A unit of RPS1 has been cloned and sequenced. It consists of 2114 bp and has a GC content of 40 mol%. The repeat unit contains smaller repeats of about 80-170 bp which are called REP1, REP2, REP3, REP4 and REP5; REP2 is duplicated. The small repeats are classified into two groups by their homology. One comprises REP1, REP2 and REP5, and the other REP3 and REP4. They are termed the REP1 and REP3 families, respectively. The two families both contain a common 29 bp sequence, called COM29. The dispersed repetitive sequence RPS1 may be involved in chromosomal rearrangements and may in part explain chromosome polymorphism in C. albicans. The origin of RPS1 was not determined.