In 3 relatively large samples intersexuality was found in 0.2 % of the pigs. Litters with intersexes had a deficit of male piglets. The total number of piglets in such litters was correspondingly reduced. Pig losses until the age of 5 weeks were reduced in intersex litters. Other malformations, especially scrotal hernia, were more common in these litters than in normal ones. Forty-five intersexes showed big variation in the development of sexual organs. All had testicles, however. Thirteen (29 %) were so-called true hermaphrodites whereas 32 were male pseudohermaphrodites. All 42 cases being karyotyped were genetical females. There are arguments for genetical predisposition for the defect. The hereditary transmission is probably complicated. In any case it is not monogenic recessive. Practical consequences of the defect are: almost complete sterility, slaughter losses due to bad smell and taste of the meat and increased risk of cassation (local or general inflammations), increased frequency of other malformations in litters holding intersexes.