Cytokines contribute to the maintenance of successful pregnancy and have also been implicated in the initiation of labour. This study has examined those cytokines which may be involved in normal term parturition. IL-6, IFN-gamma, IL-8 and GM-CSF levels were measured by ELISA in samples of amniotic fluid, peripheral and uterine venous blood plasma, and umbilical artery blood plasma from non-labouring women undergoing elective caesarean section at term and from women in spontaneous labour. IFN-gamma and IL-6 were detected only in amniotic fluid and not in blood plasma samples, unlike IL-8 which was found in all amniotic fluid and plasma samples from both labouring and non-labouring women; GM-CSF was undetectable in all samples examined. Levels of IL-6 were significantly raised in the amniotic fluid of women in labour compared with the control group (P = 0.008). IFN-gamma was detected in the amniotic fluid of both labouring women and the control group, and there was also a significant correlation (P = 0.003) between IFN-gamma and IL-6 levels in individual amniotic fluid samples. The presence of both IFN-gamma and IL-8 in amniotic fluid, as well as IL-6, suggests these cytokines are involved in important immunobiological events relevant to the latter half of gestation.