The effects of ambient and elevated ozone (O3) levels on photosynthesis, growth, pigment, biomass and element contents of Aleppo pine (Pinus halepensis Mill.) were studied for two growing seasons (1997, 1998). Two-year-old seedlings were exposed to elevated O3 in open-top chambers. The treatments were charcoal-filtered air and non-filtered air + 50 nl l–1 O3 (24 h per day, 7 days per week). In summer 1998, half of the seedlings were drought-stressed (leaf water potential down to approximately –2 MPa), while the other half were kept well-watered. At the beginning of the season (1998), current (c) and previous-year (c + 1) needles under O3 stress showed an increase in stomatal conductance and net photosynthesis. During the drought period, only stomatal conductance increased in both needle age-classes, whereas the net photosynthesis decreased. At the end of the measuring period, both parameters were reduced in the O3 treatment. Both O3 and drought decreased chlorophyll a and b concentrations, growth and biomass. A carry-over effect of O3 on pigments was also observed. Needle K content was increased in the O3 treatment. Drought protected Aleppo pine against O3 (less chlorotic mottle and less decrease of stem and branch biomass).