Scandinavian boiled coffee and coffee oil raise serum cholesterol and alanine aminotransferase (ALT) in humans. The diterpenes cafestol, and possibly kahweol, are responsible; every 10 mg of cafestol raises serum cholesterol by 0.13 mmol/L, and ALT by 5 U/L. Diterpenes are present in unfiltered coffee in oil droplets but also in coffee bean particles, of which their availability is unknown. Availability of cafestol and kahweol from coffee bean particles: Unfiltered coffee types contain 2-5 g of floating bean particles per liter of brew. We examined availability of diterpenes from spent coffee grounds in a parallel study with healthy volunteers. Intake of 8 g of fine grounds per day for three weeks increased cholesterol by 0.65 mmol/L (95% Confidence Interval, 0.41 to 0.88 mmol/L) and ALT by 18 U/L (95% CI, 4 to 32 U/L) relative to controls (n=7 per group). Floating coffee fines could thus contribute substantially to the effects of unfiltered coffee on serum cholesterol and ALT. Measurements in coffee brews should include the contribution of fines. Levels of cafestol and kahweol in various coffee brews: We developed a gas chromatography method for determination of coffee diterpenes in brews and applied it to a wide range of coffees. Scandinavian boiled coffee contained (mean /- SD) 3.0 /- 2.8 mg, French press coffee 3.5 /- 1.2 mg and Turkish/Greek coffee 4.7 /- 4.3 mg of cafestol per cup. Consumption of five cups per day of any of these coffee types could elevate serum cholesterol by 0.2 - 0.3 mmol/L. Italian espresso coffee contained 1.6 /- 1.0 mg of cafestol per cup, five cups raising cholesterol by 0.1 mmol/L. Diterpenes in instant, drip filtered and percolated brews were negligible. Regular and decaffeinated coffee had similar diterpene contents. High chronic intake of French press coffee or Turkish/Greek coffee could thus increase serum cholesterol and coronary risk similar to that reported previously for Scandinavian boiled coffee.