Objectives: Association between carpal tunnel syndrome (CTS) and ulnar nerve entrapment at wrist remains controversial. The aim of the study has been to investigate the prevalence of Guyon’s canal syndrome amongst patients diagnosed with the CTS, occupationally exposed to repetitive wrist movements. Material and Methods: The retrospective analysis of 310 patients (268 females, 42 males) representing the mean age of 52±7 years old hospitalized for the suspected occupational CTS was performed. Results: In the analyzed cohort, 4 patients had undergone decompression of the Guyon’s canal in the right limbs. Nerve conduction studies (NCS) in the ulnar nerves performed during the hospitalization of those patients did not show any abnormalities. Nerve conduction studies revealed signs of the ulnar neuropathy (UN) at the wrist affecting exclusively sensory fibers for 6 patients. Only those 4 patients who had undergone the operation suffered from clinical symptoms of the UN before the surgery. In the case of the remaining patients, despite the NCS changes, signs suggestive of the UN at the wrist were not detected. In the case of the patients with the occupational CTS, no signs of the ulnar nerve dysfunction were recorded. Conclusions: The frequency of ulnar nerve entrapment at the wrist among patients with the CTS is lower than that already reported. The low prevalence of ulnar involvement (3.2%) for the CTS patients in our study may be related to the relatively small number of the CTS hands with the severe changes in the NCS and/or other personal factor including anatomical variation of the Guyon’s canal borders and its contents. Int J Occup Med Environ Health 2017;30(6):861–874