In this study, the role of "levator ani muscles hypertonia" among pathogenetic factors of perineal obstetric injuries is analysed. For this purpose, clinical data of 142 pregnant women, who underwent functional evaluation of perineum during pregnancy and 30 days after delivery were examined. Data here reported are not sufficient to confirm the importance of this factor within the pathogenesis of postpartum perineal deficiency. Levator ani hypertonia on one hand seems to be able to obstruct fetal progression, on the other hand it presumably constitutes, as an expression of a good voluntary control of perineal muscles, a favourable prognostic factor.