The present study was designed to measure levels of oxytocic activity in the blood of cows before, during, and after physical stimulation to the teats and udder. It was also designed to determine the relationship between these levels and intramammary pressure. Knowledge in both these areas has been lacking up to the present. Some information in these areas was obtained as a result of this study. It was found that a wide variation existed in the levels of oxytocic activity between cows. In most cows, a bulk of oxytocic activity was detected in the interval of one to four minutes after stimulation began. The activity rapidly declined to low levels, with some exceptions, between the third and fourth minute post-stimulation. This information indicates that no specific changes need to be made in the present milking procedures. / Master of Science