Evaluation of inadvertent dural puncture occuring among 308 epidural blocks done for the relief of pain from various conditions was performed. Dural puncture was suspected in 5 out of 308 epidural bloks. (1.6%) Aspiration of CSF was negative in 3 cases in which dural puncture was suspected only after developing spinal anesthesia. Of the 3 negative CSF aspirations, one case had a history of laminectomy. Adhesions of the adjacent tissues might result in the loss of flexibility and a decrease in potential epidural space which might cause dural tearing during injection and subarachoid injection of the local anesthetic followed by high spinal anesthesia. In another case, the needle tip was obstructed by tissue which led to negative aspiration of CSF and failure to feel loss of resistance. The second injection at the same site may cause subarachnoid injection of the local anesthetic through the previously perforated dura mater and in turn, lead to spinal anesthesia. In the last case, there was no reason to suspect dural puncture since the loss of resistance plus air rebound were definite and aspiration of CSF was negative, but dural puncture was suspected after the patient developed spinal anesthesia.