A program to investigate the applicability of fracture toughness test methods to high density polyethylene pipe is described. Fracture toughness test specimens cut from pipe material were tested in a precracked three-point bending test at different rates. The load versus crack opening displacement record was used in an attempt to judge the validity of the test and to determine the fracture load. This method appears to need further development for this class of materials, as the results were difficult to interpret. Use of the maximum force for tests which appeared to fail in a quasibrittle manner resulted in calculation of a fracture toughness value which generally did not satisfy validity conditions. This value was used to predict the burst pressure of pipes containing surface cracks in the longitudinal direction. The prediction of burst pressure was slightly conservative, but in agreement with the trend of the experimental results. Fractographic analysis indicates three modes of crack propagation: ductile, quasibrittle, and brittle.