Antisera to 15 allotypes of pig serum protein were raised and compared with those prepared elsewhere, within the framework of International Comparison Test of pig blood groups and polymorphic proteins and enzymes in 1987-1988. Of 15 allotypes tested 8 were found to coincide with the known GpB, GpD, GpA, Gpa, IGH3 C1, Lpb3, Lpb12, Lbr1. For 7 allotypes left, no analogues were found out. They seem very likely to be new allotypes of pig serum proteins.