Pakistan Journal of Nutrition 2009, Vol 8 (3): 208-213,The prevalence study of bovine trypanosomosis was conducted in 43 smallholder farms which were randomly selected from 350 cattle farms and seven medium scale farms purposively selected in Morogoro, Tanzania. A total of 509 and 102 cross breed and local cattle, respectively aged six months and above were used in the study. The selected animals were examined for clinical signs of trypanosomosis and thereafter screened for haemoparasites using direct blood smears and micro-centrifugation methods. The overall prevalence of trypanosomosis in cattle was 2.3% (95% CI: 1.4-3.8, n = 691). Infected animals (n = 16) had the mean rectal temperature of 39.1oC±1.03. The mean number of parasites and PCV was 8.6±13.6 and 24.8%±7.9, respectively. Specific infection rates based on trypanosomas species were 0.4%, 0.6%, and 1.3% for T. congolense, T. brucei and T. vivax respectively. A highly significant (P < 0.05) infection rate was found in cattle on farms located in northeastern part of Morogoro town (4.0%, n = 303) than those in the southwest (1.0%, n = 388, RR = 3.84, 95% CI = 1.18 - 16.98). Sex, breed, grazing system, farm size, acaricide application and chemoprophylaxis were not the risk factors for the trypanosomosis infection. It was concluded that, despite a continuous uses of chemoprophylaxis, synthetic pyrethroids, bush clearing and many other methods against tsetse flies, trypanosomosis is still prevalent in cattle in Morogoro. Animals in the livestock-wildlife interphase are at higher risk of infection. It was recommended that trypanosomosis losses due to cattle mortalities, reduced production and reproduction performance, continuous disease treatment and control costs need to be quantified. Knowing the associated losses may call for strengthening the disease surveillance, treatment and control strategies which are aimed at reduction or total elimination of the tsetse flies.