After laying hens had been dosed orally with dimetridazole (DMZ) for 3 days (50 and 250 mg/kg body weight (b.w.)) or intramuscularly, also for 3 days (50 mg/kg b.w.), the residues were determined in serum, liver, breast and thigh muscle by liquid chromatography. The limit of determination was 0.01 μg/g. The maximum concentration of DMZ was found at 1 h following application. After oral doses (50 and 250 mg/kg b.w.) no residues were found in muscle (breast and thigh) at 48 and 72 h, respectively. After intramuscular injection, residues in thigh muscle were below 0.01 μg/g at 72 h but breast muscle (injection site) still had concentrations above this level. Bioavailability (F >80%) and some pharmacokinetic parameters were determined. The elimination half‐lives from serum were 2.56 h and 2.69 h, after both oral doses, respectively, and 2.88 h after intramuscular application.