Abstract: Urine uranium excretion data for persons exposed to uranium by inhalation are analyzed Data from both chronic and single massive exposures are included, and a generalized excretion pattern, applicable to any uranium compound absorbed by inhalation, is proposed. ...It is shown that it is not usually practical to use urine samples to monitor individual exposures. Such an evaluation is possible only with a suitable series of samples collected at known intervals past the exposure. It is also shown that it is not possible to determine chronic exposure levels from routine urine samples. Chronic exposure levels and body burdens can only be estimated with a sample series collected two or more weeks after the termination of exposure.