In this paper, the morphology development during shear flow of an aqueous two-phasic biopolymer mixture consisting of gelatin and dextran is studied. Two shear conditions are considered: steady shear flow and a sudden increase in shear rate. In both cases, the structure is monitored by microscopy and by small angle light scattering. During steady shear flow, it is demonstrated that a unique morphology is in practice only obtained whenever the shear rate exceeds a certain critical value. Upon a sudden increase in shear rate, the break-up of the droplet/matrix structure is monitored. It is shown that under the low shear rates considered in this paper, the scientific relations that govern the behaviour of synthetic polymer mixtures also apply to the aqueous biopolymer mixtures. (C) 2003 Elsevier Science Ltd. All rights reserved.