In this positron emission tomography (PET) study in humans we determined the pharmacokinetics and radiation dose of oxygen-15 labelled butanol, a recently introduced tracer for regional cerebral blood flow (rCBF). This report includes a description of the automated preparation of 15O-butanol which allows repetitive activation studies, each 15 min apart. Dynamic rCBF studies were extended by prolonged measurements up to 15 min after injection over different organs such as brain, liver, kidneys and bladder. All measurements were done with a whole-body PET camera PC4096-15WB. Based on the pharmacokinetic data in 13 subjects the radiation doses to single organs were calculated according to MIRD pamphlet No. 11 and the effective dose defined by ICRP 60 as an indicator of radiation dose to the total body. The liver received the highest radiation dose of about 2.2 mGy per 1500 MBq of injected 15O-butanol, which is the typical amount of administered tracer in one rCBF measurement. The dose to the kidneys was 1.6 mGy, to the stomach 0.8 mGy, and to the brain 0.16 mGy. The effective dose was 0.54 mGy, which was similar to that of H2(15)O, but lower than the effective dose from C15O2 in amounts typically applied in human rCBF studies.