A new anti-sapstain mixture, which consists of 2% IPBC (3-iodo-2-propynylbutyl carbamate) and 1.5% DCOI (4,5-dichloro-2-n-octylisothiazolin-3-one), was evaluated by three methods in the laboratory. A standardized test (JWPA standard 2) demonstrated that the new anti-sapstain formulation was highly effective in controlling growth of monocultures of five test fungi on wood substrate. When exposed to mixed spore suspension, the formulation performed better than TCP-based commercial product. A larger scale laboratory tests and supplemental trials at sawmills also supported a satisfactory performance of the formulation to protect freshly sawn timber from moulds and sapstain fungi.