Occupational ulnar neuropathy at the elbow joint develops in the course of long term direct pressure on the nerve and a persistently flexed elbow posture, but first of all, it is strongly associated with “holding a tool in a certain position” repetitively. Therefore, computer work only in exceptional cases can be considered as a risk factor for the neuropathy. Ulnar hypermobility at the elbow might be one of the risk factors in the development of occupational ulnar neuropathy; however, this issue still remains disputable. As this condition is mostly of congenital origin, an additional factor, such as a direct acute or chronic professional or non-professional trauma, is needed for clinical manifestations. We describe a patient – a computer user with a right ulnar nerve complete dislocation and left ulnar nerve hypermobility, unaware of her anomaly until symptoms of left ulnar neuropathy occurred in the course of job exposure. The patient was exposed to repetitive long lasting pressure of the left elbow and forearm on the hard support on the cupboard and desk because of a non-ergonomically designed workplace. The additional coexistent congenital abnormal displacement of the ulnar nerve from the postcondylar groove during flexion at the elbow increased the possibility of its mechanical injury. We recognized left ulnar neuropathy at the ulnar groove as an occupational disease. An early and accurate diagnosis of any form of hypermobility of ulnar nerve, informing patients about it, prevention of an ulnar nerve injury as well as compliance with ergonomic rules are essential to avoid development of occupational and non-occupational neuropathy.