© 2017 American Physical Society. The magnetic structure of the heavy fermion antiferromagnet CePt2In7 is determined using neutron diffraction. We find a magnetic wave vector qM=(1/2,1/2,1/2), which is temperature independent up to TN=5.5 K. A staggered moment of 0.45(1)μB at 2 K resides on the Ce ion. The nearest-neighbor moments in the tetragonal basal plane are aligned antiferromagnetically. The moments rotate by 90 from one CeIn3 plane to another along the c axis. A much weaker satellite peak with an incommensurate magnetic wave vector qM=(1/2,1/2,0.47) seems to develop at low temperature. However, the experimental data available so far are not sufficient to draw a definitive conclusion about the possible coexistence of commensurate and incommensurate magnetic structures in this material.