Abstract Various fracture interaction criteria were reviewed and a systematic study is presented to analyze the effect of natural fractures on hydraulic fracture propagation. From the literature review, the approach of Warpinski and Teufel was adopted to evaluat the fracture propagation that would occur after a hydraulic fracture intersects an existing natural fracture. The study determined the conditions of differential stress, angle of intersection, and fracture toughness for which dilation of the natural fracture would occur. Criteria for the subsequent modes of fracture propagation are then presented.