The use of a pesticide in the Netherlands is allowed only if it has been admitted by a government committee on the registration of pesticides. When used according to the instructions, no public health risk exists. Types and principles of bactericides, fungicides, insecticides, acaricides, and rodenticides are described, with particular attention to museum applications. The ways in which poisons are ingested and methods for self-protection are indicated. The critical doses (LD50) for animals and M.A.C. (for humans) are defined. The expertise required for the correct choice and application of pesticides is emphasized.