The concept of removing moisture from a humid drying chamber by means of condensation (dehumidification) originated a long time ago, but it was not until about 1960 that a European manufacturer took the idea and developed the first modern dehumidification drying unit. Now there are installations in numerous countries throughout the world. North America certainly presents a very lucrative market, but since the first appearance of the equipment in 1972 there has been continual debate on the advantages and disadvantages of dehumidification drying. The lumber industry required facts and unbiased opinions, and to fulfill this need the Eastern Forest Products Laboratory engaged in a program of research to evaluate dehumidification drying systems for Canadian application. Specific data on drying times, energy consumption and drying costs from actual installations, are required to properly assess the advantages and disadvantages of dehumidification drying.