Abstract: A torsion shear apparatus, especially for testing adhesives, in which two members of a test specimen bonded one into the other are subjected to a torsional load, comprising a rigid retainer for non-rotatable and form-locked retention of the first member of the test specimen, an operating member rotatably mounted in a radial bearing system in horizontal alignment with the retainer and adapted for form-locked and non-rotatable engagement with the second member of the test specimen, and a torsion-applying device for rotating the operating member relative to the retainer, characterized in that the operating member comprises a web connecting two radial bearings, each supported in a bearing support, the web being engaged by a horizontal load lever forming the torsion-applying device, and in that the retainer comprises a sliding guide portion having guide surfaces extending transversely of the radial bearings and permitting radial displacement of the first test specimen member.