This paper presents a strength criterion for intact rock, which can well describe triaxial test data under compressive or tensile stress state. The proposed criterion is defined in terms of three parameters. One parameter expresses the apparent unconfined compressive strength (AUCS), obtained from the Coulomb-Mohr criterion, as a regulated unconfined compressive strength (RUCS). Two other parameters, λ and ζ, are material-dependent that can be determined by regression analysis. The proposed criterion is compared with selected applicable strength criteria separately for compressive and tensile strengths. Coefficient of determination and accordance coefficient are considered in comparisons between the proposed and selected strength criteria.