Procedure of an examination over a gauze swab removed during a repeated operation of a patient who had undergone earlier a neurosurgical operation of a lumbar spine has been described. The extracted gauze swab became an exhibit in a case at court for financial compensation. The court commissioned to explain "if it could be placed in another way than leaving it during the former surgical operation". The neurosurgeon who performed the former operation decidedly denied that the gauze swab in question could have been left by him. Hemogenetic and histologic examination gave basis to the statement that the exhibit was left inside during the former neurosurgical operation.