The effects of water extract from Atractylodes macrocephala Koidz on biological activity were investigated. The crude water extract of A. macrocephala inhibited the growth of the dermatophytic fungus Trichophyton mentagrophytes ATCC 28185, (3 mm inhibition zone at 300 ㎍/disc). However, it did not show growth inhibition activity against Sreptococcus mutans JC-2 (MIC >1,000 ㎍/mL). This extract was cytotoxic to P388 murine leukaemia cells ATCC CCL 46 P388D1, (IC₅₀ 62.24 ㎍/mL at 150 ㎍/disc). These results suggest that water extract of A. macrocephala possesses antitumoral, and antimicrobial activities.