Monitoring of bats in hibernacula is a key element for the estimation of long-term population trends in Northern hemisphere bats. However, there is currently limited winter bat monitoring data from Ukraine, making long-term population estimates diffi cult. We present data on bat population monitoring in the largest bat hibernacula in North-Eastern Ukraine (Liptsy mines). Between 1999–2010 we conducted 115 censuses inside the three mines and counted 1150 specimens of M. daubentonii, M. dasycneme and P. auritus. 385 individuals of the same species were captured by mist-nets (39 nights). The yearly average temperature in the Liptsy 1 mine is close to the mean of annual temperature in the Kharkiv Region (about +7 °C); the humidity ranged from 85–100 %. The mean number of bats counted in a visit ranged from 1.4 to 4.9 bats, and 28 in one case. Great fluctuations in bat number were noted in Liptsy 1 and Liptsy 3–4 mines. There were high bat numbers (up to one hundred individuals on average) in the winters 2000–2001 and 2007–2008, and low bat number in winters 2002–2003 and 2003–2004. The species relative abundance for M. daubentonii was — 75–90 %, P. auritus — 7–20 %, M. dasycneme — 1–10 % respectively.