Flame photometric determinations of sodium, potassium, and calcium, moreover magnesium concentrations according to a complexometric method in 197 healthy nonpregnant women aged 16-46 years were performed in serum and fluid of the vagina. The concentrations of K+, Ca++, and Mg++ in vaginal fluid showed marked increase of some 5, 6, respectively 4 times from those of serum. The sodium concentration of the vaginal fluid is half of serum. The concentration of magnesium in vaginal fluid showed a significant increase of a quarter in comparison with serum after application of hormonal contraceptiva. The origin of vaginal fluid is discussed.