A novel improved gypsum board having improved antifungal properties is disclosed. The board comprises a gypsum core, front and back paper facings and a polymeric antifungal agent effective at inhibiting fungal growth. A preferred polymeric antifungal agent is polyDADMAC or polyTMMC. In addition to the polymeric antifungal agent, a non-polymeric antifungal agent, such as cetyl pyridinium chloride, sodium or zinc pyrithione, or both, may be included. The polymeric antifungal agent can be present in the gypsum core and/or on one or both of the paper facings. In addition, the antifungal agent may be encapsulated in a material or ionically associated with the polymeric antifungal agent, that releases the antifungal agent over time and/or upon exposure to moisture. Also disclosed are methods for preparing the aforementioned improved antifungal gypsum board.