Aquaporin 3 (AQP3) has been shown to be low in the amnion and chorion tissues of patients with oligohydramnios and that S. miltiorrhiza, a Chinese herbal medicine, results in increased AQP3 in human amniotic epithelial cells (hAECs). Here, we provide evidence for the involvement of the JNK pathway in AQP3 regulation in isolated oligohydramnios tissues in vitro, in hAECs derived from normal amniotic fluid and fluid from patients with isolated oligohydramnios. Phosphorylation of JNK was suppressed by pretreatment of cells with JNK-specific inhibitor (SP600125) and was up-regulated by S. miltiorrhiza; S. miltiorrhiza combined with SP600125 prevented SP600125-induced down-regulation of phospho-JNK both in normal amniotic fluid volume and in isolated oligohydramnios. In isolated oligohydramnios, AQP3 expression was significantly suppressed by SP600125 in a concentration- and time-dependent mannner, while its expression was up-regulated by S. miltiorrhiza. S. miltiorrhiza combined with SP600125 inhibited the increased expression of AQP3 relative to the S. miltiorrhiza treated group. Together, the data suggest that c-jun N-terminal kinase (JNK) pathway unerlies the regulation of AQP3 by S. miltiorrhiza amnion and chorion tissues.