Ferrochelatase (FECH) catalyses the insertion of ferrous ions into protoporphyrin IX to produce haem at the haem-biosynthetic pathway. The present study characterized a variant mRNA of mouse FECH, which was generated by skipping exon II (FECH-v). FECH-v mRNA was expressed in various tissues, including the liver and kidney, of mice. The mRNA was also expressed in mouse and human non-erythroid and erythroid cells to a different extent but could not be translated into functional FECH. The ratio of FECH-v/FECH increased in hemin-treated Balb/3T3 cells, while it decreased after treatment with succinylacetone, an inhibitor of haem biosynthesis, strongly suggesting that FECH expression was decreased by increasing the level of intracellular haem. These results demonstrated the haem-dependent negative feedback regulation of the expression of FECH at a post-transcriptional level.