A combined anion exchange-spectrophotometric method has been developed for the determination of vanadium and cobalt in biological materials. A sample is dry ashed at 420 °C, the ash (ca. 0.5 g) is decomposed with a mixture of perchloric, nitric and hydrofluoric acids, and finally is taken up in hydrochloric acid. The metals are adsorbed by anion exchange on an Amberlite CG 400 (SCN^–) column from a dilute ammonium thiocyanate-hydrochloric acid solution. The adsorbed vanadium and cobalt are separated chromatographically by elution with 12 M hydrochloric acid and 2 M perchloric acid, respectively. Both fractions of vanadium and cobalt are subsequently purified by anion exchange from 0.1 M hydrochloric acid-3%V/V hydrogen peroxide for vanadium and 6 M hydrochloric acid for cobalt. Vanadium and cobalt in the effluents are determined spectrophotometrically with 4-(2-pyridylazo)resorcinol. Results for the determination of vanadium and cobalt in various materials of biological origin and in NBS standard biological samples are given.