The purposes of this research were to study and compare the opinions towards the internal auditing staff’s working behaviors in Trat Provincial Health Department. The aspects of genders, ages, educational levels, job positions and departments were studied. The populations were the 162 personnel staff in the secondary care hospitals in the area of Trat Provincial Health Department. The research instrument was the five-rating-scale questionnaire with the reliability level of 0.98. The descriptive statistics were percentage, mean, standard deviation, t-test, one way analysis of variance and the LSD method.