The major objective of the Swedish Council on Technology Assessment in Health Care (SBU in its Swedish abbreviation) Chemotherapy Project was to review and assess the evidence, as presented in the scientific literature, for the use of chemotherapy in some major tumour types. The purpose of this assessment was to establish the current evidence-based role of this treatment modality in various settings in these tumour types. The basis for the assessment was the perspective of the conditions in Swedish health care and a prospective survey within the project detailed the use of chemotherapy in two health-care regions in Sweden. This formed the basis for an assessment of the use of chemotherapy in relation to scientific evidence. The project focused on standard cytotoxic chemotherapy, whether delivered at conventional doses or at higher doses with various supportive actions, and did not address the role of other emerging approaches that could broadly be included under the heading chemotherapy, e.g. drugs with anti-angiogenesis and anti-metastatic properties or chemopreventive drugs. In this introduction, the project objectives, working process, key definitions and general aspects on cancer trial methodology and interpretation are presented and discussed.