There is a significant sulphate influx in Chara australis, Nitella translucens, and Tolypella intricata but not in Nitellopsis obtusa. The uptake is active in Chara, the ions moving into the vacuole against an electrochemical potential gradient. Influx rate in the light remains constant whereas a transient increase in rate occurs upon transfer to the dark. Both the light and the dark influx rate respond similarly to temperature, and to external sulphate ion concentration. It is proposed that sulphate is pumped actively across the plasmalemma and that the increase in influx rate following transfer to the dark reflects a transient increase in the rate at which the pump operates. There is an apparent light stimulation of the tonoplast flux.