Dimethyl sulphoxide is a water miscible solvent that has wide applications in cell biology. It acts as a cryoprotective agent in a variety of cells and tissues allowing prolonged storage at subzero temperatures. DMSO has a very strong affinity for water; on exposure to air, pure DMSO is rapidly diluted. DMSO has enhanced penetration into other substances across biologic membranes; free radical scavenging; effects on coagulation; anticholinesterase activity; and DMSO-induced histamine release by mast cells.