Magnesium and calcium, as well as sodium and potassium, have an important influence on the physiology of contraction of the uterus. The ionic concentrations in the pre- and postmenopausal myometrium were examined. We assumed, that there are differences in the electrolytic contents because of the different functions of the corpus, isthmic part and cervix uteri during pregnancy and throughout labour. Small tissue samples from 37 premenopausal and 20 postmenopausal patients, who underwent an operation with different indications, were dissected after hysterectomy. Magnesium and calcium levels were determined by atomic absorption spectrophotometry and potassium and sodium by emission spectrometry in the wet tissue. In both groups, we found significant differences of the electrolytic contents of the myometrium. In the premenopausal uteri, the magnesium levels decrease significantly (p < 0.001) from the corpus (mean = 4.14 mmol/kg) to the cervix (mean = 2.14 mmol/kg). The same scenario can be observed for the potassium levels (Corpus mean = 56.2 mmol/kg and cervix mean = 25.4 mmol/kg). In contrary, the calcium levels (Corpus mean = 1.60 mmol/kg and cervix mean = 2.26 mmol/kg) and sodium levels (Corpus mean = 69.3 mmol/kg and cervix mean = 93.0 mmol/kg) increase significantly (p < 0.001). In the postmenopausal group, we found slightly elevated concentrations of magnesium, sodium and potassium. Only the calcium content of the corpus uteri rises up to three times about 20 years after the menopause (from mean = 1.60 mmol/kg) (p < 0.001). The electrolytic contents in the myometrium were shown to be different in the corpus, isthmus and cervix uteri.(ABSTRACT TRUNCATED AT 250 WORDS)