The International Olympic Committee is to retest frozen blood samples taken from athletes during the Beijing Games in August for traces of a new generation of drug.
The decision follows a number of positive cases involving frozen samples of cyclists from the Tour de France in July.
The IOC said on Wednesday it will especially be looking for EPO CERA, a new performance-enhancing drug that the cyclists tested positive for.
Continuous Erythropoiesis Receptor Activator is a form of EPO that has a longer lasting effect in improving the blood's oxygen delivery system.
The IOC collected about 1,000 blood samples and about 4,000 urine samples during the Games in Beijing.
Once a urine test for the substance is available the urine samples will also be tested.