The results of an experimental test program performed to investigate the influence of specimen dimensions and testing rate conditions on room temperature fracture toughness of PP homopolymer are presented. The material displayed nonlinear load-displacement behavior and exhibited small amounts of slow crack growth (ductile tearing) prior to cleavage instability, which invalidates the direct application of the current standards for the determination of K-IC in polymers. Data points were considerably scattered consistently with typical ductile-brittle transition patterns. The resulting load-displacement diagrams were analyzed in terms of K-Q, K-MAX, and the ratio P-MAX/P-Q. The fracture toughness at instability, J(C), was also computed and plotted against the amount of stable crack growth in order to construct J-R curves as a function of size and strain rate. From these curves an alternative critical fracture parameter, K-JIC, was calculated. Weibull statistics were used as a tentative approach for treating the scatter of fracture toughness of polypropylene homopolymer in large samples, which exhibited restricted ductile tearing. The significance of each of these methods and the validity and size independence of the corresponding parameters are discussed.