Phycotoxins are metabolites synthesized naturally by marine algal and cyanobacteria species. They accumulate in the marine organisms and eventually cause poisoning in humans. Phycotoxins include chemical compounds such as amino acids, alkaloids, and polyketides. Most of these chemical compounds are toxic in nature but some of them can be harnessed for useful purposes such as preparation of medicines for certain ailments. Phycotoxins have also found their use in production of beneficial materials such as Botox and other therapeutic agents. Research studies need to be conducted to exploit and harness the potential of these algal products that can be used for benefit of mankind.