Powder x-ray diffraction experiments have been done on Ne up to 237 GPa at room temperature. Ne remains in the fcc phase up to the highest pressure. In order to observe the weak 200 reflection at ultrahigh pressures, we have used the tube-cross slit at the exit side of x-rays, which effectively reduced the scattered x-rays by the diamond anvil. The lattice parameters obtained from the 111 and 200 reflections significantly differ from each other, implying the existence of sizable uniaxial stress in Ne at ultrahigh pressures. On the basis of the calculated elastic constants of Ne at high pressures, we conclude that the 111 reflection is least affected by the uniaxial stress. The equation of state constructed from the 111 reflection agrees well with previous data. © 2010 IOP Publishing Ltd.