Local and temporal expression of CCK(A) and CCK(B)/gastrin receptor genes was studied in the calf with a quantitative Reverse Transcription-Polymerase Chain Reaction (RT-PCR) method. Cerebral cortex, antrum, fundus, gall bladder, pancreas and liver were analyzed in calves at 0, 2, 7, 21, 28 and 150 days of age. Cerebral cortex and pancreas expressed both receptor genes with a ratio between CCK(A) and CCK(B)/gastrin receptor transcripts varying according to the age. Gall bladder and fundus showed an exclusive expression of CCK(A) and CCK(B)/gastrin receptor mRNAs, respectively, with the highest levels of transcripts in newborn and 28-day-old calves. The rank order for CCK(A) receptor mRNA expression was gall bladder > pancreas > cerebral cortex > antrum and that for CCK(B)/gastrin receptor mRNA expression was cerebral cortex / pancreas / fundus > antrum. No CCK(A) and CCK(B)/gastrin receptor mRNA was detected in liver, regardless of the age of calves. The present data represent a basis for a better understanding of the ontogeny of physiological functions linked to the CCK(A) and CCK(B)/gastrin receptors.