To determine whether needle size influences a patient's perception of pain, 50 patients requiring hormonal manipulation for prostate cancer were blindfolded and randomised to receive two goserelin ('Zoladex') or two leuprorelin ('Prostap') injections, using 16- or 23-gauge needles, respectively. Median visual analogue scale pain scores for the first injections of goserelin and leuprorelin were below the level of clinical significance and were not statistically different. Mean administration time for goserelin was significantly shorter than for leuprorelin. In conclusion, there was no statistically significant difference in pain experienced on injection of goserelin and leuprorelin when patients were unaware of needle size.