Spectrofluorometric assays were carried out on the blood fractions and some cardiovascular tissues of both sexes of chickens, ducks and pigeons to determine histamine levels. Cardiac tissue histamine ranged between 0.15 and 5.82 μg/g in both females and males of these three species; the chicken had the highest concentration. Atrial tissue histamine was higher than that found in the ventricles; males usually had higher concentrations than females. The relevance of these values to other biogenic amines are discussed. Splenic histamine ranged from 3.17 to 15.21 μg/g; the female had higher values than the males. Of all the blood fractions, the white blood cells contained the highest levels; the plasma contained the least. Histamine concentration in whole blood ranged from 0.33 to 0.90 μg/ml in chickens, 0.07 to 0.14 μg/ml in ducks, and 0.02 to 0.09 μg/ml in pigeons. The blood fractions of female birds showed higher histamine values than those of males.