Six new bisabolane type sesquiterpenoids, cheimonophyllons A (1), B (2), C (3), D (4), E (5), and cheimonophyllal (6) were isolated from the culture fluid of the basidiomycete, Cheimonophyllum candidissimum. The compounds exhibited nematicidal, weak antifungal and antibacterial as well as cytotoxic activities. The main product, cheimonophyllon A (1) (C₁₅H₂₂O₄), was also active in the Ames mutagenicity test.