This paper presents the results of a survey of 1021 cattle in the southeastern area of Nigeria during August–October 1990 (wet season) and January–March 1991 (dry season) to study the effects of season, ecological zone, management system, breed and age on the occurrence of gastrointestinal parasites (GIP).Strongyles (mainly Haemonchus spp.) were the commonest GIP (prevalence 47.8%; 95% CI; 44.8–51%; mean eggs per gram (epg) 387 ± SE 21.3) followed by coccidia (3.6%; 95% CI, 2.6–5%; mean oocysts per gram (opg) 2077 ± 778.4). The prevalence of other parasites encountered was comparatively very low. More infections were present in the wet than in the dry season (P<0.01). Whereas a higher prevalence (P<0.01) of strongyle infection was recorded in nomadic herds, that of coccidia was higher in sedentary herds. The prevalence of strongyle infection was lower in young animals (P<0.05), but they had higher epg (P<0.01) and also higher coccidia prevalences (P<0.01) than adults. Friesian and N’dama breeds under improved management in modern farms had lower strongyle and higher coccidia infections compared with zebu and muturu kept under the traditional management system The distribution of infection by ecological zone did not show any consistent trend, and this was attributed to the uneven distribution of the cattle breeds amongst the different zones.