The cDNA encoding histamine H4 receptor was cloned from the porcine spleen cDNA library. Porcine H4 receptor, which shares 72% homology with its human counterpart, bound to histamine in receptor-expressing mammalian cells. Isolation of the porcine H4 receptor, which is important for understanding of the pharmacology, will aid in better interpretation of physiological role of this subtype of histamine receptor.