Abstract: A goniometric device particularly for X-ray or neutron diffractometry on monocrystals or any other sample comprises a sample-holder to maintain the monocrystal to be analyzed in the axis of the incident X-ray or neutron beam. Means for driving this sample-holder on itself, about a first axis, and also in rotation about a second axis perpendicular to the first and a third axis perpendicular to the second. The sample-holder is borne by a slave-goniometer comprising a transverse bar made of ferromagnetic material fast with the sample-holder, therefore perpendicular to the first axis of rotation of the sample-holder on itself. The sample-holder is rotatably mounted onto a support forming part of a universal joint mounted on a fixed base and of which the two perpendicular axes correspond respectively to the second and third axes of rotation.