Specimens of the posterior pubo-urethral ligament were taken from 10 continent females (7 at post mortem and 3 at gynaecological surgery) and from 9 genuine stress incontinent patients. They were examined and compared using light and electron microscopy and neuro-histochemistry. The morphology of all specimens was similar in that they contained dense connective tissue elements enclosing smooth muscle bundles which were associated with numerous nerves, the enzyme content and fine structure of which were similar to those believed to represent cholinergic autonomic nerves. There was no difference in the morphology, histochemistry and fine structure of the specimens of the ligaments from the control and incontinent patients. Therefore, it is suggested that altered morphology of the posterior pubo-urethral ligaments is unlikely to be an etiological factor in genuine stress incontinence. It is postulated that the ligaments may play a role in stabilising the proximal urethra or assist in bladder-neck opening during voiding.