Abstract. This article reports a rapid and effective method for the extraction and purification of genomic DNA (gDNA) from individual first-stage larvae (L 1 ) of elaphostrongyline nematodes that had been stored frozen or fixed in 95% ethanol for 1 to 5 years. The method was highly effective for L 1 s of all 6 species of elaphostrongylines, based on polymerase chain reaction (PCR) amplification of a partial fragment of the first internal transcribed spacer (ITS-1) of the ribosomal DNA. Differences were detected in the sizes of partial ITS-1 amplicons between the 2 elaphostrongyline genera, Elaphostrongylus and Parelaphostrongylus. The reliability of the ITS-1 PCR assay was tested by using L 1 s of unknown identity from Newfoundland and Labrador, Canada. The ability to consistently isolate gDNA from individual L 1 s, together with a simple PCR-based method to distinguish between Parelaphostrongylus and Elaphostrongylus, have important implications for diagnostic testing and for conducting epizootiological studies on these parasites of veterinary importance.Key words: Diagnosis; DNA extraction; Elaphostrongylus; Parelaphostrongylus; PCR.Elaphostrongyline nematodes (Elaphostrongylus spp. and Parelaphostrongylus spp.) occur in the central nervous system and/or skeletal muscles of cervids and can produce verminous pneumonia and, in some cases, severe neurologic disease. 13 Four of the 6 species of elaphostrongyline, Parelaphostrongylus tenuis, Parelaphostrongylus andersoni, Parelaphostrongylus odocoilei, and Elaphostrongylus rangiferi, occur in North America. 13 Elaphostrongylus rangiferi also occurs in northern Fennoscandinavia and Russia. 13 Elaphostrongylus alces occurs in Fennoscandinavia, whereas Elaphostrongylus cervi occurs in Eurasia and New Zealand. 13 Elaphostrongylus rangiferi was introduced to the island of Newfoundland with reindeer (Rangifer tarandus tarandus) from Norway in 1908, 14 where it subsequently spread to infect woodland caribou (R. tarandus caribou) and moose (Alces alces). 15 Woodland caribou in Newfoundland are also infected with P. andersoni; however, this parasite is significantly less pathogenic than is E. rangiferi in this host species. 13 It is believed that E. rangiferi has not spread with caribou from Newfoundland to mainland Canada; however, this needs to be confirmed. 4 The first-stage larvae (L 1 ) of the elaphostrongylines and of several other genera (e.g., Varestrongylus, Muellerius, and Umingmakstrongylus) within the family Protostrongylidae have a characteristic dorsal spine on their tail. 2 The L 1 s of Muellerius and Varestrongylus can generally be distinguished from the elaphostrongyline L 1 s by their shorter length, 9 whereas Umingmakstrongylus occurs only in muskoxen (Ovibos moschatus). 12 Diagnosis of elaphostrongyline infection in cervids is often based on the detection of L 1 s in feces 4,16 ; however, the larvae cannot be identified to the species or genus level because of their morphological and morphometric similarities. 3,4,13 Sometimes the identities of L 1 s are...