Water relations parameters, proline content as well as leaf anatomical characteristics were studied in olive cultivar (Olea europea (L.) cv. picual) grown under different levels of available water. The results clearly show that total osmotic adjustment increased and the relative water content decreased with increasing severity of drought. Drought stress resulted in an increase of the upper and lower epidermis and significantly decreased the palisade parenchyma, spongy parenchyma and the total leaf thickness with a parallel increase of the free proline content.