MnCit improves mean base-calling accuracy for the rhodamine and dRhodamine dye-terminator sequencing kits, but not for the BigDye kit. The template pGEM3Zf(+) was sequenced with either the M13F or the −21/pUC primer. The unedited base calls obtained using the different sequencing kits (without or with the addition of the optimal concentration of MnCit) were aligned with the known sequence of pGEM3Zf(+). The percent miscalled bases was determined for each 50-nucleotide increment, as measured from the 3′ end of the sequencing primer. In the increment 1–50, the error rate calculations do not include bases not detected, but only those incorrectly called. The mean dRhodamine values are based on 6 and 10 sequences in the absence (▴) and presence (▵) of MnCit, respectively. The mean BigDye values are based on four and six sequences in the absence (◼) and presence (■) of MnCit, respectively. Error bars are not shown for clarity.