Clonidine produces analgesia via a non-opioid mechanism and it may be used as an interesting adjuvant to local anaesthetics and opioids in obstetric analgesia. To examine the effects of the addition of clonidine to bolus injections of bupivacaine, adrenaline and sufentanil, we enrolled 50 women receiving extradural analgesia for vaginal delivery into a double-blind study. They were allocated randomly to two groups: group A received a 10-ml extradural solution of bupivacaine 12.5 mg combined with adrenaline 25 micrograms and sufentanil 10 micrograms; group B received the same solution with clonidine 30 micrograms. Each patient was allowed two subsequent injections of the chosen solution. Subsequently, if still in the first stage of labour, analgesia was augmented with additional 10-ml injections of bupivacaine 12.5 mg with adrenaline 25 micrograms, without sufentanil or clonidine. The latter solution was used for perineal analgesia in group A; clonidine 30 micrograms was added in group B. During the first and second stages of labour, there was no difference between the two groups in duration of analgesia after the first injection (142 min in group A; 127 min in group B), number of injections (1.8 in group A; 1.9 in group B) and the total bupivacaine requirements (33.9 mg in group A; 34 mg in group B). The quality of analgesia was evaluated as very good in both groups (23/25 in group A; 24/25 in group B). The degree of motor block or the frequency of other side effects were not enhanced by clonidine.(ABSTRACT TRUNCATED AT 250 WORDS)