This paper provides an extensive review of different aspects of five shellfish-poisoning syndromes (paralytic, diarrhoeic, amnesic, neurologic and azapiracid), as well as one fish-poisoning syndrome (ciguatera fish poisoning), and discusses in detail the causative toxins produced by marine organisms, chemical structures and analytical methods of the toxins, habitat and occurrence of the toxin-producing organisms, case studies and existing regulations. Based on this analysis, risk assessments are carried out for each of the toxins, and recommendations are elaborated to improve the management of these risks in order to reduce the harmful effect of these toxins on public health.