A survey of gastrointestinal helminth parasites of stray dogs (Canis familiaris) was conducted at Obollo-Afor and Ekwulobia markets, in Enugu and Anambra States, south-eastern Nigeria, respectively, to determine the patterns of infection among dogs in different parts of south-eastern Nigeria. Faecal samples collected, using long forceps, from every dog encountered in the markets between June 2007 and December 2008 were analysed by the Kato-Katz technique. Out of 413 dogs examined in both markets, 217 (52.6%) were infected with at least one of five parasites (Toxocara spp., Dipylidium caninum, Ancylostoma caninum, Taenia spp. and Trichuris vulpis). Overall faecal egg intensity of infection was 49.9 ± 58.7 eggs/g (epg). The prevalence of infection was comparable between the markets and between the male and female dogs, but varied significantly (P < 0.05) by age, decreasing from 78.9% in pups to 36.0% in adult dogs. The mean intensity pattern was similar to that of prevalence, decreasing from 86.7 ± 63.0 epg in pups to 22.1 ± 34.4 in adults. The most important individual parasite infection was Ancylostoma spp. (39.2%; 30.0 ± 41.2 epg) while T. vulpis was the least important (1.9%; 0.7 ± 5.4 epg). Generally, prevalence and intensity patterns of each parasite were also comparable between the markets and between sexes, but significantly (P < 0.05) age-dependent. The implications of these findings to public health in Nigeria and other endemic countries are discussed in relation to options for cost-effective control design and implementation.