Creosote oils contain hundreds of compounds. During impregnation and handling of treated wood the main component in the vapors released in air is naphthalene. Other main components are alkyl naphthalenes, indene, phenol and its methyl derivatives, benzothiophene, diphenyl, acenaphthalene and fluorene. In the measurement of creosote vapors, naphthalene can be used as an indicator agent. One of the major urinary metabolites of naphthalene is 1-naphthol. To explore the relation between naphthalene concentration in the air and 1-naphthol in the urine of exposed workers we monitored air concentrations and collected urine samples from six men over a working week. 1-Naphthol concentrations in urine samples were analyzed by GC as a pentafluorobenzylbromide derivative. The average concentration of 1-naphthol in the Monday morning samples was 0.1 mg/l, in the Monday afternoon 3.1 mg/l, in the Friday morning 0.4 mg/l and in the Friday afternoon 2.9 mg/l.