Peanut is a major crop of the southeastern USA. Considering the prediction of frequent and severe droughts in future and increasing competition of water in Georgia, studying water-use efficiency (WUE) of peanut is vital. The impact of single and twin-row planting patterns on WUE of peanut has given less attention. Hence, this study used the eddy-covariance method to compare CO2 flux, H2O flux and WUE of single and twin-row planted peanut for 2016 and 2018. The study indicated that when precipitation was not a limiting factor, both CO2 flux (7-10 %) and WUE (~9%) of twin-row planting pattern was greater than single-row in the mid and late growth stages of peanut. However, CO2 flux and WUE was not different for different planting patterns in water was a limiting factor during these stages. Furthermore, the H2O flux was not different for single or twin-row planting pattern regardless of water availability.