The distribution, excretion and metabolism of 1,4-dimethylnaphthalene following i.p. administration of a single dose of 28 mg/kg to rats, was investigated using radiotracer [3H] and gas chromatography-mass spectrometry technique (GC-MS). After 72 h, about 97% of the given dose was excreted in urine and faeces. Maximum level of tritium in plasma was observed during the 4th h. after the compound administration. In organs and tissues, the highest concentration during the first hours after administration was detected in the fat, liver, spleen and kidneys. Then gradual decline in tritium was noticed in all examined tissues. In urine the following substances were identified and quantified by GC peak areas: unchanged 1,4-dimethylnaphthalene, 1-hydroxymethyl-4-methylnaphthalene, 4-methyl-1-naphthoic acid, 1,4-dimethylnaphthol, 4-methyl-1-naphthoic aldehyde and 1,4-dimethyl-methylthionaphthalene.