In a comparative compilation of partly unpublished test data on the efficacy of wood preservatives against fungi and insects, brown-rot and soft-rot fungi as well as Hylotrupes larvae are considered and termites mentioned. A survey on the most important types of wood preservatives is given and an abbreviation easy to learn and consisting of letters, which show the decisive constituents of the preservatives, is suggested. Problems of the testing of wood preservatives, with respect to the evaluation of test results, are briefly dealt with. Comparing the test results on the efficacy of wood preservative in the form of critical and toxic values, separations were made according to wood under shelter and in the open air as well as water-soluble and oily preservatives. The conciseness of this summary does not permit to repeat numerical data. The preservative types are compared with regard to their efficiency and durability of effectiveness, and the problems of reducing laboratory tests to practice as well as facts and condition of application are discussed.