The saxitoxin class of algal toxins (cyanotoxins) are neurotoxins produced in Australia by the blue-green alga (cyanobacterium) Anabaena circinalis. A range of water treatment processes was investigated for the removal of these compounds. Ozonation of the toxins at moderate doses was found to be ineffective. Chlorination was found to be effective at high pH; therefore where pH adjustment is possible in the treatment process, chlorination could be considered as an important treatment option. Activated carbon, both in the granular and powdered form, was effective for reducing the toxicity of a mixture of the toxins as the most toxic of the saxitoxins were also the most readily removed by adsorption.