The transcobalamin II (TC II) polymorphism in the Swiss population is described. The typing method is given in detail. The following gene frequencies were observed: TC II1 0.4242, TC II2 0.0121, TC II3 0.5584, TC II4 0.0030 and TC II5 0.0023. The system is an informative parameter in paternity testing. The average chance of exclusion is 20%.