Purpose: Dental implant macrogeometry parameters, such as the prosthetic connection and implant body shape, can influence the biomechanical behavior of the restoration. Using tridimensional finite element analysis (3D-FEA), this study evaluated the biomechanical behavior of two implant macrodesign parameters (prosthetic connection and implant body shape) in low-quality bone. Materials and Methods: Four groups were obtained by the combination of external hexagon and Morse taper connections, and cylindrical and conical body shapes. Implants (4ø × 10-mm) with a microthread collar and triangular thread shape received a single abutment and monolithic zirconia crown on the maxillary first molar. Bone was constructed on the basis of cross-sectional images of the posterior human maxilla obtained by cone beam computed tomography. A 200-N axial loading was distributed on five points of the occlusal surface. Data were acquired as shear stress (τmax, in megapascals) and strain (εmax, in micrometers) in the cortical and trabecular bone. Results: The external hexagon groups generated higher shear stress/strain values compared with Morse taper groups in the cortical bone, regardless of implant body shape. In the trabecular bone, the highest τmax and εmax values were observed in the Morse taper conical implant group (6.94 MPa and 21.926 × 10-4 μm, respectively), and the lowest values were observed in the external hexagon cylindrical implant group (4.47 MPa and 9.3155 × 10-4 μm, respectively). Conclusion: The magnitudes of shear stress and strain in the peri-implant region of low-quality bone was lower with the use of Morse taper connection and cylindrical implants compared with external hexagon connection and conical implants. Keywords: dental implant, finite element analysis, implant body shape, osseointegration, prosthetic connection