A comparison of the symptomatology, haematology and prevalence of trypanosomiasis in Holstein Friesian and White Zebu cattle exposed to natural infections on a ranch in a rain forest zone of Nigeria is presented. 23 (44%) of the adult Friesians had trypanosome infections with a generally heavy parasitaemia. Infection was light in the Friesian calves and the Zebus with infection rates of 2 (6.9%) and 3 (15%) respectively. Trypanosoma vivax was the sole species encountered on the farm. There was a general unthrifty appearance in the adult Friesian herd as well as classical signs of trypanosomiasis. The Friesian calves and Zebus were generally in good conditions with an appearance of good health except one each of the infected animals which showed apparent symptoms of the disease. There was a marked reduction of the red cell values of the infected adult Friesian and Zebu cattle. The red cell values of the uninfected adult Friesians were equally depressed suggesting cryptic infections or that they were cured parasitologically by the recently administered trypanocide. The Friesian calves had normal red cell values for both the infected and uninfected. Leucocyte counts were generally high on the Farm and higher for the infected animals.