Calcium alginate capsules containing Aureobasidium pullulans cells were prepared by an in-situ one-step method. The Cd-2+uptakes of `free biosorbent' and `capsule biosorbent' were described well by the Freundlich isotherms. The Cd-2+ uptake of `capsule biosorbent' was lower than that of `free biosorbent' with Cd-2 +at 100 mg l(-1). The total cadmium uptake of `capsule biosorbent' increased with the increase in encapsulated cell density and plateaued at a value of 23 mug Cd-2+/capsule with 150 g dry biosorbent l(-1) core volume of a capsule. The specific cadmium uptake of encapsulated biosorbent was 85% to that of `free biosorbent' at 35 g biosorbent dry weight l(-1) core volume of a capsule, decreased to 35% at 176 g biosorbent dry weight l(-1).