This paper reviews the state-of-the-art in interlaminar fracture testing of composite materials, with particular emphasis on the work performed in Portugal over the last 15 years. Early work, carried out within the ESIS Polymer and Composite Technical Committee, was concerned with improving test methods on unidirectional [0degrees](n) specimens. The focus was on the mode I double cantilever beam (DCB) test and on mode II end-notched flexure (ENE) and end loaded split (ELS) tests. In spite of some remaining controversy on mode II testing, the main issue nowadays is fracture toughness measurement on multidirectional specimens. Remaining difficulties are discussed in the light of the most recent work. Guidelines for ongoing and future research are also presented.