In a prospective study of 80 patients under 40 years of age, given spinal anaesthesia through either a 0.52 mm (25-gauge) needle or a 0.33 mm (29-gauge) needle, the incidence of post-dural puncture headache and backache was compared. There were no headaches in the 0.33 mm needle group, while in the 0.52 mm needle group an incidence of 25% was found. The incidence of backache was the same in both groups. The technique of performing spinal anaesthesia was evaluated and concluded to be slightly more difficult with a 0.33 mm needle, as estimated by the number of redirections of the needle needed to obtain cerebrospinal fluid. There were no differences between the two needles with respect to obtaining adequate spinal anaesthesia and spread of blockade.