The incidence of postdural puncture headache after spinal anaesthesia with two types of 26- and 29-gauge needles was investigated in 149 patients less than 30 years old. Ten patients, (6.7%), six men and four women, developed typical symptoms of postdural puncture headache, while six (4.0%) developed headache of other origin. There were no headaches in the 29-gauge group. Spinal anaesthesia in four patients (8%) was impossible to perform with the 29-gauge needle. By using the latter, spinal anaesthesia can be given to young adults with little risk of postdural puncture headache.