In the yeast Saccharomyces cerevisiae, DNA synthesis preceding meiosis requires the expression of replication genes used during mitosis. Diploids carrying either a temperature-sensitive lesion in cdc4 (a gene required for initiation of mitotic DNA synthesis) or a lesion in cdc8 (a gene controlling mitotic polymerization) completed premeiotic DNA synthesis at a permissive but not at a restrictive temperature. The roles of cdc4 and cdc8 were evaluated by characterizing the kinetics of  premeiotic DNA synthesis after a shift to a restrictive temperature. In the cdc8 diploid, DNA synthesis was immediately inhibited, consistent with a role in polymerization. In contrast, cdc4 exhibited residual DNA synthesis characteristic of an initiation function. The cdc4 gene function was completed much earlier in the meiotic cycle than the cdc8-mediated step.