The determination of protein in aqueous media by using commercial and laboratory-prepared test-strips has been investigated. Adsorption indicators of the Bromophenol Blue type form the basis of the colour-forming reaction, which is selective for natural protein. The relative precision of reflectance measurements is 1.7-5.7% over the concentration range 0.5-10 mg ml , for bovine serum albumin. The method would be suitable for the rapid determination of protein in urine and other body fluids.