The Falcon assay screening test-enzyme-linked immunosorbent assay (FAST-ELISA) and the enzyme-linked immunoelectrotransfer blot (EITB) technique were used to test human sera with Dracunculus medinensis adult worm antigen in order to assess their potential value in the immunodiagnosis of dracunculiasis. The human sera used were from patients with prepatent and patent D. medinensis infections or from patients infected with other nematodes (Onchocerca volvulus and Loa loa) or trematodes (Schistosoma mansoni and S. haematobium), as well as uninfected Nigerian and Puerto Rican normal controls. In the FAST-ELISA, the sera from prepatent and patent dracunculiasis patients gave the highest absorbance values relative to normal human sera. The highest cross-reactivity was observed with onchocerciasis sera; no cross-reactivity was seen with sera from individuals with loiasis or schistosomiasis mansoni or haematobia. By the EITB, sera from dracunculiasis patients specifically recognized a 16 kDa protein (Dm 16) and antibodies to Dm 16 disappeared 2 months after worm extraction. Recognition of Dm 16 occurred from the late prepatent stage. A 17 kDa protein (Dm 17) was also recognized by dracunculiasis sera, but antibodies to Dm 17 disappeared more slowly and were present 1 year after recovery. The 16 kDa and 17 kDa antigens of D. medinensis may be useful in the immunodiagnosis of dracunculiasis.