Abstract. In this paper, first we introduce minimal and closed monotone DNF formulas as extensions of maximal and closed itemsets. Next, by incorporating the algorithm dnf cover designed by Hirata et al. (2003) with the algorithm Charm designed by Zaki and Hsiao (2002), we design the algorithm cdnf cover to extract closed monotone DNF formulas with a pruning as same as dnf cover. Finally, we implement cdnf cover and apply it to bacterial culture data.