The ternary semimetal CuMnAs is a half-Heusler alloy with antiferromagnetic order [1, 2] and it crystallizes orthorhombically in the space group Pnma (No. 62) Antiferromagnetic materials could represent future of spintronic applications due to numerous specific features and their combinations. Recently [3] it has been shown that in CuMnAs Dirac fermions could be present. Massless Dirac fermions were found to emerge as low-energy excitations in materials now known as Dirac semimetals. These semimetals have received an enormous amount of attention due to the wide range of exotic physical phenomena theoretically predicted [4]. The observation of fermions in a magnetically ordered material has a fundamental character. So far there are no experimental data on the magnetic structure of bulk orthorhombic CuMnAs and neutron diffraction studies will provide a picture of the magnetic ordering in this compound. The aim of the experiment is to get information on the magnetic structure of CuMnAs.