Cryopreservation of finfish and shellfish sperm has a longer history thanthat of eggs and embryos hence with a fruitful result. The first part of thispaper introduces the principles of cryopreservation including cryofreezing,thawing and cryogenic storage. The second part describes five major injuriesrelated to freezing and thawing in the generalized cryopreservation procedures.They are pH fluctuation, cold shock, ice crystal formation, permeability andtoxicity of cryoprotectants. The third part discusses the basic steps affectingsperm survival in the series of freezing procedures and compares for thosesuccessful finfish and shellfish species in Taiwan. The steps are (1) collectionand assessment of sperm, (2) equilibration of cells in extender andcryoprotective agents, (3) freezing of sperm suspension using controlled oruncontrolled cooling rates, (4) cryogenical storage at -196(C, and (5) thawingof frozen sperm for fertilization.