At present, spinal anesthesia is often recommanded for a safe operation and the management of pain. However the complications from the spinal anesthesia, such as hypotension, dyspnes, nauses and vomiting, pulmonary embolism, headache, auditory and visual disturbances, lumbago, urinary difficulty and neurologic sequelae have often reported from time to time. Thus an attempt to study the complications of spinal anesthesia, particularly the differences of complications between needle sizes(22 gauge and 25 gauge), has been done by our department. The following results were observed: 1) The most common sequelae of spinal anesthesia was hypotension(35.6%) and in order frequency, urinay difficulty(23.3%), headache(16.7%), lumbago(15.3%), nauses of and vomiting(12.8%), dyspnes(8.9%), auditory and visual disturbances(0.83%) and minor neurologic sequelse(0.56%). 2) The incidence of headache and lumbago was more frequent in the 22G, group, but there were no statistically significant differences(p>0.05). 3) The incidence of headache was higher in the females than the males and there were statistically significant differences(p<0.01). 4) The incidence of lumbago was higher in the fourth decade (21.7%), and females showed a higher incidence than in males and there were statistically significant differences(p<0.05). 5) The incidence of lumbago and headache and the degree of headache was without correlation to the number of punctures in both groups(22G group and 26G group). 6) The time to postoperative urination had no correlation to the level of anesthesia.