ABSTRACTBiological specimen collection is an integral part of many longitudinal epidemiological studies. It is important to achieve high participant satisfaction for continuing involvement, and high sample quality for accurate biomarker measurement. We conducted a study to evaluate these issues on the sample collection proposed for the Canadian Longitudinal Study on Aging (CLSA). There were 85 participants recruited, and 65 attended either a hospital laboratory or private laboratory. Approximately 100 mL of blood and a random urine specimen were collected from each participant for a total of 2,108 sample aliquots. Quality standards were met for more than 90 per cent of samples and were similar for samples collected in both laboratories. More than 90 per cent of participants rated satisfaction with the collection as being good or excellent, and 84 per cent would be willing to repeat the collection in one to three years.