Chromosomal mutations (eight translocations, two pericentric inversions, one paracentric inversion) were found in 8 of 30 phenotypically normal pigs derived from semen irradiated at 800 rads. There were no chromosomal mutations detected in pigs derived from semen irradiated at 600 rads. A summary of the spontaneous and induced cases of chromosomal mutations in the family Suidae suggests that chromosomes 1 and 15 are more often involved in rearrangements.