Thyrotoxic periodic paralysis is a rare and serious complication of thyrotoxicosis that can present as transient attacks of muscle weakness usually associated with hypokalaemia. Certain activities have been shown to commonly precede these attacks including a high carbohydrate intake, strenuous exercise and a heavy alcohol intake. This effect can be explained by an increased activity of Na / K ATPase in myocytes as a result of these activities. However, this does not fully explain the pathogenesis of this condition and it appears that a complex interaction between genetic and environmental factors is involved. Recently, genetic mutations in two channel types involved in potassium homeostasis: Na / K ATPase and inward rectifying potassium channels, have been shown to be associated with this condition by increasing the risk of hypokalaemia. However, the low prevalence of these mutations in Asians, who have the highest prevalence of this condition, suggests that there is a more complicated pathophysiology, which requires further research to be fully understood.