The objective: to determine the efficacy of sublingual forms of micronized progesterone (Luteina) in treatment of women with preterm labor. Patients and methods. 45 women with preterm labor were examined in 24–35 weeks of gestation. 2 subgroups were formed. Subgroup Ia consisted of 23 women, who received micronized progesterone sublingually in complex treatment, subgroup IB consisted of 22 pregnant women, who didn’t receive progesterone. 56 case reports of premature births were analyzed retrospectively. The main group of pregnant women underwent general and biochemical examination, determination of ALT, AST, total bilirubin and progesterone. Results. Risk factors for preterm labor during observation in the antenatal clinic were established. They included the underestimation of anamnesis, incomplete examination, delayed treatment of threatened preterm labor, insufficient prevention of complications of pregnancy. It was established that the levels of both AST and ALT as well as total bilirubin in serum hadn’t change after the treatment in both subgroups of women from I group. The decrease in the serum level of progesterone was observed in both subgroups. Average concentration of progesterone in blood serum increased up to 1108±39 nmol/l on the third day of treatment in the subgroup Ia, and it reached 1260±42 nmol/l on the seventh day, whereas its dynamics practically didn’t chang in subgroup IB (882±33 nmol/l and 893±31 respectively). The use of sublingual form of micronized progesterone in the complex treatment of women with preterm labor gave the opportunity 2 times to decrease frequency of premature births, 1.5 times to decrease frequency of delivery complications, almost 2.5 to improve perinatal consequences compared to subgroup of women who hadn’t use progesterone. Conclusions. 1. Risk factors of preterm labor are delayed first prenatal visit of pregnant women to antenatal clinic, the underestimation of anamnesis and risk factors for the development of gestational complications, incomplete examination, delayed treatment of threatened preterm labor, incomplete prevention of pregnancy complications. 2. The use of sublingual forms of micronized progesterone in cases of signs of preterm labor permits to restore quickly the level of progesterone in blood serum to physiological parameters, 2 times to decrease the frequency of premature births and 2.5 times to decrease perinatal consequences in infants. 3. The use of sublingual form of micronized progesterone in pregnant women with preterm labor does not affect the function of the liver. 4. The obtained results allow to recommend the wide use of sublingval form of micronized progesterone to pregnant women with preterm labor. Key words: preterm labor, treatment, Luteina.