We validated seven chronic disease ascertainment algorithms for use in the Canadian Longitudinal Study on Aging. The algorithms pertained to diabetes mellitus type 2, parkinsonism, chronic airflow obstruction (CAO), hand osteoarthritis (OA), hip OA, knee OA, and ischemic heart disease. Our target recruitment was 20 cases and controls per disease; some cases were controls for unrelated diseases. Participants completed interviewer-administered disease symptom and medication use questionnaires. Diabetes cases and controls underwent fasting glucose testing; CAO cases and controls underwent spirometry testing. For each disease, the appropriate algorithm was used to classify participants' disease status (positive or negative for disease). We also calculated sensitivity and specificity using physician diagnosis as the reference standard. The final sample involved 176 participants recruited in three Canadian cities between 2009 and 2011. Most estimated sensitivities and specificities were 80 per cent or more, indicating that the seven algorithms correctly identified individuals with the target disease.