An earlier epidemiological and electron microscopy study of drinking water in the Everett area of Washington State indicated large numbers of naturally occurring chrysotile asbestos fibers in the water. The purpose of the present study was to determine whether significant numbers of asbestos fibers could be demonstrated in the urines of donors resident in that area for less than 3 years and over 20 years the tap water contained about 200,000,000 fibers/liter. A control group was obtained from Seattle where the tap water asbestos fiber content was 100 x less. Urines, filtered control water, tap water samples, and additional controls were processed for transmission electron microscopy by the use of the Nuclepore membrane filter-Jaffe wick procedure. At present, the data is inconclusive but would suggest no relationship between high concentrations of fibers in drinking water and the numbers estimated for voided urine.