This issue is a sample of current work in Portugal on diverse topics within the broad field of fatigue, fracture, structural integrity and related areas. The common feature of the papers included is the authorship by researchers of several Portuguese universities and other organizations, although in some cases the articles include co-authors from other countries such as France, Romania, the United Kingdom and the United States. The work presented in this issue covers composites and metals, involving experimental and numerical tools and concepts. It includes papers on topics such as biaxial fatigue, welded connections, pressure vessels, rolling contact, and aspects of the fatigue behaviour of aluminium alloys. Structural integrity studies of gas turbine discs, exhaust pipes of naval turbines, fighter aircraft, and cold worked cracked holes for fuselage applications are presented. As far as composites are concerned, studies on interlaminar fracture, intralaminar cracking and fracture of composite co-cured joints are included. Fatigue and fracture research in Portugal is the subject of regular Portuguese Conferences on Fracture organized by the Sociedade Portuguesa de Materiais (SPM). The 9th edition of this series, started in 1983, took place in Setúbal on 18–20 February 2004, and was included in the calendar of the European Structural Integrity Society (ESIS). In parallel with these national events, which usually attract a number of experts from other countries, several international meetings already took place in Portugal. To give just two examples, the ESIS 6th International Conference on Biaxial/Multiaxial Fatigue and Fracture, Lisbon, 25–28 June 2001, and the early 5th European Conference on Fracture, 17–21 September 1984, organized in the context of the European Group on Fracture (predecessor of ESIS), may be mentioned. Joint events with the Spanish researchers—the Iberian conferences—are occasionally organized, and these started with an event in Braga in 1987. The active community of researchers in the field, and the natural good conditions, make Portugal an interesting location for organizing these scientific meetings as indicated by the 1st International Conference on Engineering Failure Analysis ICEFA-1, Lisbon, 12–14 July 2004, or proposed future events in the context of the European Mechanics Society (EUROMECH). A relatively small country of approximately 10 million inhabitants, Portugal has seen a substantial increase in research and development activities since the 1970s. This is a result of several factors, among which should be mentioned a large concentrated effort of training academic staff in foreign universities started in the beginning of 1970s. In the areas of interest for this journal, that policy was translated into practice by Professor Luciano Faria in Lisbon (Instituto Superior Técnico of the Universidade Técnica de Lisboa— IST), and by Professor Vasco Sá in Porto (Faculdade de Engenharia da Universidade do Porto—FEUP). Among others, they led the selection and created conditions for the training of the first generations of experts in these fields, which took place principally in the United Kingdom and France. More recent decades witnessed the development of the research capacity in the country. In parallel there is an increasing internationalization of the activity, with frequent stays in Portuguese universities of post-doctoral researchers and visiting professors in the context of programmes such as the NATO post-doctoral scholarships or the U.S. Fulbright Commission, participation in European Union and other international R&D projects, and joint supervision of doctorates by Portuguese researchers in foreign universities, and by foreign researchers in Portuguese universities. The editors of Fatigue and Fracture of Engineering Materials and Structures (FFEMS) approved in 2002 a suggestion for the publication of a special issue concerning research in Portugal. The result, now in the hands of the readers of the journal, is a series of papers that went through the usual refereeing process of this journal. I would like to express my gratitude to the authors and referees. As Guest Editor of this issue, I am indebted to the editors of FFEMS, and to Professor Eann Patterson in particular, for encouragement and interest in this project.