The first Scandinavian symposium on monoclonal antibodies in cancer was held in June 1989, in Umeb, Sweden, the second one in August 1990 in Lund, Sweden, and this third meeting in October 1992 in Helsinki, Finland. The fourth symposium is planned to be held in 1995 in southern Norway. The two-day Helsinki symposium included clinical and experimental studies related to radioantibody research on cancer detection and therapy. The national coordinators were Sven-Erik Strand and Torgny Stigbrand (Sweden), Magne Aas (Norway) and Jesper Zeuthen (Denmark), to whom the local organizers express their deep gratitude. The main goal of the symposium was to assemble researchers in this field, needing knowledge of immunology, radiochemistry, radiation physics, molecular biology, clinical oncology, etc. Research and development of radiolabeled antibodies for clinical use are time and cost consuming and require special skill .and therefore already existing forces should co-operate. Special exchange programs, Scandinavian multicenter clinical trials, etc. should be developed. This meeting assembled a total of 90 participants. They came from all the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden) but also from Germany, UK and USA. There were 34 presentations, including 11 reviews. The clinical part consisted mainly of reviews on radioimmunodetection in various malignancies (melanoma, prostate cancer, ovarian cancer, breast cancer, lung cancer, head and neck cancer) but there were also two plenary presentations of clinical radioantibody research in Hammersmith Hospital, London (Dr AA Epenetos) and in Memorial Sloan-Kettering Cancer Center, New York (Dr SM Larson). The participation of these two experienced plenary speakers is gratefully acknowledged by the organizers. The experimental sessions dealt with topics related to animal model selection, dosimetry, radiolabeling, antigen selection, and applications in xenografted animal studies. Also technical improvements, such as beta-camera, diffusion chambers, and positron emission tomography were presented. It is our great privilege to present the major contributions to the symposium in Acta Oncologica. The financial support from funds from Nordisk Forskningsuddalseakademi, Nordic Cancer Union, Ministry of Culture of Finland, Finnish Society of Nuclear Medicine, and from the companies Behringewerke AG, Marburg, Germany, Meda Oy, Helsinki, Finland, and MAP Medical Technologies Inc., Jyvaskyla, Finland, made this symposium possible.