Groundwater is one of the major sources of exploitation in arid and semi-arid regions. Thus for protecting

groundwater quality, spatial and temporal distribution of data are important. The objective of this

research was to evaluate interpolation methods for predicting spatial distribution of some groundwater

quality such as TDS, Na+, EC, SAR, Cl- and SO4

-2. Data related to 65 wells in Rafsanjan plain were used

and IDW, kriging and cokriging were studied. After normalization of data, variograme was drawn. For

selecting suitable model for fitness on experimental variograme, less RSS value was used. By using crossvalidation

and RMSE, the best method for interpolation was then selected. Results showed that for interpolation

of groundwater quality, kriging and cokriging methods are superior to IDW method. At last, the

maps of groundwater quality were prepared, using the best interpolation method in GIS environment.