The abilities of different species of seaweeds and their derivatives to remove a range of heavy metals from solution under standard laboratory conditions were determined. The three species of brown seaweeds were Ecklonia maxima, Lessonia flavicans and Durvillea potatorum. The two seaweed derivatives produced by commercial seaweed processing were alginate fibres and dealginated seaweed waste. The abilities of these biomasses to sequester the heavy-metal ions copper, nickel, lead, zinc and cadmium from solution under constant agitation were compared. The effect of the presence of more than one metal ion in solution was investigated in order to determine whether any competition effects might have affected metal-ion uptake. The metal-removal capacity of these seaweeds and their derivatives is discussed in the light of the economic and environmental aspects of using such a wastewater-treatment system on an industrial scal