Regional trend analyses of monthly pan evaporation data were conducted using the regional average Mann-Kendall test with both serial and cross-correlation at 66 sites in Turkey for 1975-2006. Regional increasing trends identified in monthly data have appeared to be predominantly insignificant all over Turkey with the strongest magnitude in May through August. However, majority of the regions exhibited insignificant decreasing trends in April. Increasing regional trends were in the Eastern Anatolia, Mediterranean Sea, Central Anatolia, Southeastern Anatolia. Marmara and Black Sea regions and decreasing trends in the Aegean region. When averaged the Sen slopes across the sites in a region over a 30 year period, the increase in monthly pan evaporation ranged between 2.7 and 44.1 mm or 2.1-25.7% whereas the decrease varied between 1.9 and 19.8 mm or 0.7-19.7% throughout Turkey. The implication of these results is that the terrestrial surface in Turkey has, on average, become more arid in the recent 30 years for May through October except the Aegean region.