A new spirocyclic diketopiperazine alkaloid, namely, 7-O- methylvariecolortide A (1), together with recently reported known compounds variecolortides A-C (2-4), were isolated and identified from the liquid fermentation cultures of Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of the stems of the mangrove plant Hibiscus tiliaceus. The structures of these compounds were determined by extensive analyses of their spectroscopic data.