The ultrasonic pulse velocity (UPV) in water-saturated concrete is higher than in dry concrete. However, moisture influence on the UPV is defined within a wide range: — from negligible to quite significant (16 per cent). The nature of "UPV − concrete moisture" correlation is also interpreted in different ways — both as linear and as exponential. This paper reviews how various degrees of moisture saturation influence the UPV in concrete when sounding is carried out by the frequently used ultrasonic testing method — the indirect transmission by using longitudinal wave pulse. Research was conducted on specimens hardened both under standard conditions and at elevated temperatures. The results show a sudden UPV increase at the degree when the maximum water absorption in concrete is achieved.