|Abstract:||The purpose of this study was to obtain DNA sequence information from the HIS4 gene on chromosome III from a large number of independently arising, spontaneous His$\sp+$ revertants of the +1 frameshift mutation his4-38 in Saccharomyces cerevisiae strains XY729 (REV1) and XY760 (rev1-1). To accomplish this, two methods were employed, the double-strand repair of gapped plasmids, and the polymerase chain reaction (PCR). Both approaches permitted the recovery of DNA sequence alterations from an unmodified eukaryotic chromosome. DNA sequence information from 44 independent XY729 spontaneous His$\sp+$ revertants was obtained using double-strand gap repair. The PCR was used to recover DNA sequence information from 95 XY729 and 93 XY760 independent spontaneous His$\sp+$ revertants. Over 85% of the total sequence alterations responsible for the reversion of his4-38 were $-$1 deletions, but +2 insertions, $-$4 deletions, $-$7 deletions and complex mutations were also observed. Ninety-five percent of the sequence alterations observed in the reversion of his4-38 were consistent with current models of frameshift mutagenesis. Between strain XY729 (REV1) and strain XY760 (rev1-1) there was a general difference in the overall pattern of single base deletions and other mutation events. In strain XY729, the distribution of mutation events was bimodal, while in strain XY760, the mutations were more evenly distributed. This could reflect the absence of the REV1 function in strain XY760. In addition to this, there was a significant difference between the types of sequence alterations recovered using the repair of a gapped plasmid (only single base deletions and one +2 insertion), and those recovered using PCR (single base deletions, +2 insertions, larger deletions and insertions, and complex mutations). This difference may reflect a selectional mechanism inherent in double-strand gap repair that avoids chromosomal sequences which include complex alterations.