The influence of transcutaneous nerve stimulation (TNS) on the hormonal parameters of placental function (HPL and Estriol) in the serum of 39 patients between the 28th and 39th week of pregnancy was investigated. In this patients placental insufficiency was suspected because of low hormonal parameters or a diminished radioisotope placental perfusion test. During a hospitalization of 2 weeks these patients underwent a daily TNS-therapy for 2-3 hours. 2 or 3 hormonal values before these two-weeks therapy and 2 or 3 values after the therapy were compared. A significant difference (p less than 0.05; t-test) was found. HPL and Estriol mean values raised absolutely, but also in comparison to a group of patients of our clinic without placental insufficiency. A correlation between the onset of therapy at a certain week of gestation and it's effect could not be proved. The use of this riskless method as a therapy of placental insufficiency is recommended.