In the first stage of a prospective cardiovascular health survey, 2955 males aged 34-61 years were invited for examination during a 12-month period. The response was 75%. Appointments were arranged in such a way that all age groups would be equivalent with respect to time of day, weekday and time of year on which appointments were given. In fasting blood and urine samples the following quantities were estimated: s-alkaline phosphatase (AP), s-bilirubin (Bil), s-creatinine (Cre), s-uric acid (UA), haemoglobin (Hb), haematocrit (Hct), mean cell haemoglobin content (MCHC), erythrocyte sedimentation rate (ESR) and urine specific gravity (USG). The approximate 5% and 95% centiles were as follows: (table; see text) No indication of seasonal variation was found in these results.