Abstract: The integrity coefficient of rock mass presents general quality and strength of rock mass. It is an important input parameter in many analysis of rock mass behavior such as in rating of rock mass integrity and quality and rock mass classification. However, there are divergences in relevant codes on how to determinate and apply the integrity coefficient. This paper discusses the contributing factors on determination of integrity coefficient. It then suggests that the elastic wave velocity of intact rock and rock mass for calculation of integrity coefficient be measured in the similar weathered rocks with the same geophysical method. Otherwise, the measured value has to be corrected. The openness and filling conditions of discontinuities should be carefully considered when the integrity coefficient is estimated with the volumetric joint number. In rock mass classification and estimation of rock burst, the term ratio of rock mass strength to ground stress has different geological implications. The rock mass strength has relation with integrity coefficient of rock mass.