Dear Editor,rnWe present herein the isolation and characterization of detergent-resistant membranes (DRMs) from rat spermatozoa.This is the first study on rat sperm DRMs.rnDetergent-resistant membranes including lipid raft and caveolae are cholesterol-and sphingolipid-rich microdomains of the plasma membrane that concentrate components of certain signal transduction pathways.1 They are receiving increasing attention as devices involved in the regulation of membrane fluidity and membrane protein trafficking.