The crystal structure, lattice strain due to the antiferromagnetic ordering, and magnetic form factor in the itinerant 5 f compounds U T Ga 5 (T= N i, P d, Pt) have been studied by neutron scattering. High-resolution powder diffraction revealed that the tetragonality of the U-Ga layers increases down to the series of the transition metal element T. The integrated intensities of the antiferromagnetic reflections can be well explained with the Néel-type structure for UNiGa 5, whereas UPtGa 5 has the antiferromagnetic stacking of the ferromagnetically ordered uranium moments in the c plane. In both compounds the uranium moments orient along the c axis with moments of 0.75 (5) and 0.32 (5) μ B for UNiGa 5 and UPtGa 5, respectively. No magnetic peak could be observed in the powder diffraction pattern of UPdGa 5 due to the small magnetic moment less than the experimental sensitivity. The orbital contributions in the magnetic form factor are reduced from the free-ion value, especially for UNiGa 5. This suppression shows a strong correlation with the bulk susceptibility. We observed lattice anomalies associated with the antiferromagnetic ordering. The tetragonality of the U-Ga layers is a sensitive measure of the nearest-neighbor interaction, the lattice anomaly and the orbital contribution suggest that orbital degrees of freedom may play an important role for the magnetic properties in these itinerant 5 f antiferromagnets.