A novel non-radioactive DNA diagnostic method has been developed to detect Plasmodium falciparum infection in whole blood. In this method a drop of blood from a finger prick is added to a lysing solution containing a biotinylated oligonucleotide whose sequence design is based on the repeated sequence of the parasite genome. The mixture is heated in a boiling water bath and then added to a microtitre plate where the 'target-bioprobe hybrids' are captured by the immobilized oligonucleotides. The plate is then washed to remove the coloured material and the biotinylated oligonucleotide retained on the plate is assayed by streptavidin-alkaline phosphatase conjugate. This method has also been tested in field trials by double-blind studies to detect P.falciparum infection in blood samples. Results indicate that this method is superior to the classical blood smear examination for its speed and its ease in large epidemiological surveys and is especially useful in identifying clinical malaria in endemic areas where the semi-immune population predominates. The method described can be of general application for the detection of any foreign pathogen in blood, other body fluids and tissue samples, provided the DNA probe employed constitutes a part of the repeated sequence of the genome and is unique.