Abstract: The aim of the study was to evaluate the effect of histamine receptor antagonist on right ventricle’s function in broiler chickens with pulmonary hypertension induced by low ambient temperature. One hundred and sixty male 17-day-old broilers were divided randomly into four groups. There are forty birds in each group. (1) Normal temperature group (NT): The birds were reared at 22-23 ℃and normal saline was given twice by intramuscular injection each day. (2) Low ambitent temperature group (LT): The birds were reared at 9-11 ℃and normal saline was given twice each day. (3) Chlorphenamine maleate group in low ambient temperature (CMLT): The birds were reared as LT, and chlorphenamine maleate was given twice each day. (4) Cimetidine group in low ambient temperature (CLT): The birds were reared as LT, and cimetidine was given twice each day. At 24, 31, 38, 45 days of age, 7 birds were randomly taken from each group for measurement of right ventricular pressure (RVP) using right cardiac catheter. Mast cells (MC) was stained with Alicience blue. Histamine was shown using immunohistochemistry. The ascites heart index (AHI) were accounted. The results were as follows: (1) The number of mast cells and histamine positive cells were decreased by low ambient temperature, but it was no affected by chlorphenamine maleate and cimetidine. (2) The RVP of CMLT group was maintained at same levels, and the RVP of CLT group was kept at low levels. (3) The dp/dt of CMLT group was significantly (P<0. 05) different with that of LT group. (4) AHI of LT group was significantly higher than that of NT and CMLT group (P<0. 05). (5) The ratio of right ventricular hypertrophy and failure in CMLT group were lower than those in LT group. It was concluded that internal histamine can promote the development of pulmonary hypertension syndrome by dysfunction of right ventricle through H1 receptor in broilers.