Pyknocytosis is a transitory erythrocyte-related condition which can result in severe anemia and hyperbilirubinemia. Recognition of pyknocytes by microscopic analysis of a blood film is essential for a correct diagnosis. Treatment consists of correction of the anemia by top-up blood transfusion and light therapy to prevent toxic bilirubin buildup. High levels of free unconjugated bilirubin could be the underlying cause for the formation of pyknocytes.