This is a report about a 9 year old turkish boy suffering from recurrent 
episodes of high fever caused by Plasmodium vivax-infection (Malaria tertiana), 
12 months after returning from his malarious homeland. After a 3-day course of 
Chloroquin, we administrated Primaquin to eliminate residual extraerythrocyte 
forms of Plasmodium vivax. On the 7th day of treatment acute haemolysis 
developped. This was caused by Glucose-6-Phosphate-Dehydrogenase-Deficiency, 
which could be demonstrated by a red-cell-enzyme analysis. The investigation of 
the patient's whole family showed the typical recessive X-linked inheritance of 
this enzyme-defect. Frequency and clinical manifestations of this defect are 
discussed.