In proliferating S. cerevisiae, genes whose products function in DNA replication are regulated by the MBF transcription factor composed of Mbp1 and Swi6 that binds to consensus MCB sequences in target promoters. We find that during meiotic development a subset of DNA replication genes exemplified by TMP1 and RNR1 are regulated by Mbp1. Deletion of Mbp1 deregulated TMP1 and RNR1 but did not interfere with premeiotic S-phase, meiotic recombination or spore formation. Surprisingly deletion of MBP1 had no effect on the expression of CLB5, which is purportedly controlled by MBF. Extensive analysis of the CLB5 promoter revealed that the gene is largely regulated by elements within a 100 bp fragment containing a cluster of MCB sequences. Surprisingly induction of the CLB5 promoter requires MCB sequences, but not Mbp1, implying that another MCB binding factor may exist in cells undergoing meiosis. In addition full activation of CLB5 during meiosis requires Clb5 activity suggesting that CLB5 may be regulated by a positive feedback mechanism. We further demonstrate that during meiosis MCBs function as effective transcriptional activators independent of MBP1.