Cattle tick control remains a serious problem in cattle farms worldwide, due to the limited success achieved with chemicals. Although the use of vaccines for tick control may open possibilities for an integrated approach, the search for other protective antigens is still necessary to improve control. Boophilus microplus is a rich source of BmTIs, serine proteinase inhibitors that are present throughout the tick's lifecycle. The present paper reports a pen trial conducted to evaluate the performance of a synthetic BmTI N-terminal fragment as antigen against the tick in bovines. The trial was conducted with two groups of eight crossbred cattle under controlled infestation: one group was vaccinated with BmTI peptide using saponin as adjuvant and the other was kept as control. Challenge was performed with 15,000 larvae. The specific IgG response was measured by ELISA, with successful outcomes for vaccinated animals. Vaccination resulted in an 18.4% level of efficacy when compared with the control group.