Based on the case of a young miner with paraesthesias of the fingers working with the risk of vibrations and excessive overloading of the upper extremities the authors demonstrate the case of a less frequent Martin-Gruber anastomosis type III. Its diagnosis was preceded by two discrepant electromyographic findings from different laboratories. The final diagnosis was established only by the third electromyographic examination made by a neurologist – longstanding consultant for occupational diseases. The co-existence of distal neuropathy of the median nerve on the right wrist with abnormal innervation of the right hand was reported as an occupational disease according to the appendix of Government regulation no. 290/1995 chapter II, item 7. Abnormal innervation is according to the literature encountered in 15–30 % of the population and can influence in a fundamental way the resultant finding and conclusion. It has to be taken into consideration always when evaluating the occupational character of disease. In the conclusion the authors emphasize the importance of permanent consultants for occupational diseases.

        Key words: Martin-Gruber’s anastomosis, neuropathy, electromyographic examination, occupational disease