1. The neurohypophysial hormone activities were detected in extracts of the median eminence and the pars nervosa of parakeets, ducks and chicken. The results so far secured suggest that in composition of the neurohypophysial hormones the median eminence contains more arginine vasotocin and less oxytocin than does the pars nervosa.2. Histologicial observations revealed that the neurohypophysial hormone activity of the two regions was in close relation to the amount of neurosecretory material contained in the regions.3. Results of inactivation experiment and enzymatic digestion confirmed the presence of oxytocin and arginine vasotocin in the chicken median eminence and pars nervosa. Furthermore, these two peptides were eluted separately through chromatography on ion exchange resin.