The stable isotopic composition of oxygen and hydrogen (δ 18 O and δ 2 H) and the tritium activity (A) were monitored in precipitation at synoptic station Portorož (Slovenia) during the period 2007-2010. Monthly and yearly isotope variations are discussed and compared with those observed over the period 2001-2006 and with the basic meteorological parameters. The mean values for δ 18 O and δ 2 H, weighted by precipitation, are-6.28 ‰ and-41.6 ‰, and these values are 0.35 ‰ and 1.6 ‰ higher but not significantly different than for the period 2001-2006. The reduced major axis (RMA) local meteoric water line (LMWL RMA) for the period 2007-2010 is δ 2 H = (8.14 ± 0.25)×δ 18 O + (8.28 ± 1.64), while the precipitation weighted least square regression (PWLSR) results in LMWL PWLSR δ 2 H = (7.87 ± 0.28)×δ 18 O + (7.97 ± 1.87). The deuterium excess (δ) weighted mean value is 8.6 ‰ and is 1.2 ‰ lower than in 2001-2006, while the temperature coefficient of δ 18 O is 0.21 ‰/°C and is for 0.02 ‰/°C higher than for the previous period. The mean Mediterranean precipitation index (MI) for the period 2007-2010 is 2.3. Lower values of MI and deuterium excess than in the preceding period indicate stronger continental climatic character during observation period, however the differences are not statistically significant. The weighted mean tritium activity is 6.4 TU, which is 0.5 TU lower but not significantly different than in 2001-2006. Izvleček V prispevku obravnavamo izotopsko sestavo kisika in vodika (δ 18 O in δ 2 H) ter aktivnosti tricija (A) v mesečnih vzorcih padavin, ki smo jo spremljali na sinoptični postaji Portorož (Slovenija) v obdobju 2007-2010. Analizirali smo mesečne in letne spremembe izotopske sestave padavin in jih primerjali z nizom podatkov za obdobje 2001-2006 ter z osnovnimi meteorološkimi parametri. Srednje tehtane vrednosti δ 18 O in δ 2 H določene ob upoštevanju izmerjene količine padavin znašajo