Developments in technique and equipment during the 1960's in freezedrying at the Smithsonian Institution are described and illustrated. While the principal application has been to prepare vertebrate animal specimens in natural form with minimum tissue shrinkage, the museum has extended freeze-drying to the preservation of fresh anatomical specimens, arthropods and their larvae, and pathological tissues already fixed in formalin. The latter involve neutralization of the formalin with either hexamethylenetetramine or ammonium hydroxide. The successful freeze-dry treatment of a waterlogged booklet which had been submerged for over a century is outlined. Differences between the techniques of freeze-drying museum specimens and related procedures of preserving foods or pharmaceuticals are noted.