There are typical causes for carpal tunnel syndromes as well as a series of rare causes. Furthermore, the clinical image can also be untypical. This report is about a 59-year-old female patient with an untypical clinical symptomatology and with a rare cause: there was no major pain during the night or in the morning, no paraesthesias and no impairment of the fine motor skills, nevertheless, there were rapid paraesthesias and pain in the first three fingers of the right hand immediately after hyperextension of the wrist. Although the discomforts had already existed for 2 years they were not recognised properly because they were untypical and incomplete and neurography was negative. 3 years later in a renewed examination X-ray pictures of the carpus were taken and a 4 x 6 x 8 mm big ossicle on the ground of the carpal canal was found, the computed tomography and the intraoperative situs confirmed the image. The histology gave the diagnosis of a loose osteochondral body. Postoperatively the patient was quickly was free of the symptoms.