At the dawn of 21st century, phycoremediation has received significant attention as a feasible technique for arsenic removal from contaminated water. Here a study was attempted to assess the potential of microalgae Chlorella sp. CB4 to remove As(III) and As(V) from aqueous phase in optimized conditions. Removal efficiency achieved for As(V) was 87% and for As(III) was 86% in optimized condition. In groundwater the removal efficiency was 64% for As(V) and 75% for As(III). Chlorella sp. CB4 provided a viable option for treatment of As laden water.