The phase transition of the three-dimensional spatially anisotropic Ising antiferromagnetic model in the presence of an uniform longitudinal magnetic field H is studied by using the traditional Monte Carlo (MC) simulation for sizes L=16, 32 and 64. The model consists of ferromagnetic interactions Jz=λ2Jx in the x(z) direction and antiferromagnetic interactions Jy=λ1Jx in the y direction (Ising superantiferromagnetic). For the particular case λ1=λ2=1 we obtain the phase diagram in the T-H plane. Was observed first- and second-order transitions in the low and high temperature limits, respectively, with the presence of a tricritical point. © 2013 Elsevier B.V. All rights reserved.