The analgesic effects of transcutaneous electrical nerve stimulation (TENS) in labour and effects on outcome were investigated in a double-blind TENS/TENS placebo controlled trial in 100 primigravidae and 50 women in their third labour. There were no differences between the TENS and the TENS placebo users in terms of pain concept or relief, and only 12 and 13% of primigravidae and 48 and 39% of the para 2 women completed labour without requiring other analgesia in their respective groups. The primigravidae who used either TENS or TENS placebo alone had shorter labours than those who required further analgesia. Although the outcome of labour for mother and infant were similar in the two groups, there was a higher operative delivery rate in women who also had epidural analgesia. There were highly significant differences between the TENS and the TENS placebo users in terms of favourable and unfavourable comments by the mothers and the midwives at 1 and 24 h after delivery. The evident consumer satisfaction for TENS suggests TENS has a part to play in analgesia in labour but the equivocal findings in terms of factors associated with pain relief points to the need for apparatus more specifically designed to cope with the special characteristics of the pain of labour.