Fetal bovine serum (FBS) is an important component of the in vitro cultivation medium for trypanosomes. The study describes the in vitro cultivation of Trypanosoma congolense IL3000 procyclic forms in 109-c medium supplemented with different concentrations of FBS. Supplementation of 109-c medium with 20% FBS produced the shortest duration (in days) of the parasite’s restriction phase whereas 5% FBS resulted to the longest parasite restriction phase. The highest peak of parasite growth (1.24 x 107 cells/ml) was obtained using 109-c medium with 10% FBS. It was exhibited that procyclic forms slowly but successfully adapted to medium with 5% and 10% FBS after more than a month of cultivation. The data demonstrated that the concentration of heat inactivated fetal serum was not directly proportional to the rate of parasite multiplication. The results suggest that 109-c medium supplemented with 10% FBS is a cost-efficient medium for good growth and morphology and maintenance of Trypanosoma congolense procyclic forms in vitro. Furthermore, considering the cost factor and animal welfare considerations, 109-c medium supplemented with 5% FBS appears to be an appropriate medium for the prolonged continuous in vitro cultivation andmaintenance of the parasite stock in the laboratory.