The objectives of this cross-sectional population study of 70-year-old people in Gothenburg, Sweden, were to make a survey of the social and medical conditions of the population, to obtain basic data for planning the care of the elderly, to contribute to the knowledge of normal ageing processes and of normal criteria within the age group, and to offer the subjects a thorough medical examination. A representative systematic sample comprised 1 148 propositi (521 males and 627 females). The study comprised a homecall part regarding basic personal data, dwelling conditions, economy, social and physical communications, previous migration, educational level, previous and any present professions, need for care, consumption of health care and drugs. Observations and measurements were done of illumination at the habitual site of reading, and a simple test of visual acuity was performed. Later on, examinations at the Out-patient Department of the Geriatric Hospital were performed, comprising in all probands general medical and ophthalmological examination, blood and urine sampling, ECG and X-ray of heart, lungs, and breasts and on subsamples, psychological, psychiatric, dental, somatometric, and audiometric examination. Furthermore, a dietary interview and a body composition examination were performed on subsamples. This first presentation deals with the design and procedure of the study, analysis of observer variation and a comparison between responders (85%) and non-responders (15%). The general design of the study, the sampling procedure, and general methods of data collection were found to be adequate. The responders were found to be representative for the population as a whole in most respects studied. The results of this study to be reported in subsequent papers will in general allow conclusions regarding the population of 70-year-olds in Gothenburg.