Abstract: The Penman-Monteith equation is used to estinate potential evapotranspiration in Guizhou province based on the daily meteorobgical observations from 18 stations during the period 1961-2001.The estimation of potential evapotranspiration is alms achieved by adopting simple model approaches, such as the radiation-based and the temperatore-based models.The Penman-Monteith potential evapotranspiration is comparedwith these simple model estimates.Results show that allmodels are able to well estimate the long-tern annualmean potential evapotranspiration with relafive errors less than 0.05%.However, large variations are found among simulated annual mean potential evapotranspiration series.The radiation-based models perforn better than the temperature-based ones in comparison with the Penman-Monteith potential evapotranspiration, which suggests that the radiation-basedmodels are more applicable for future climate change studies in Guizhou province.