The morphology of GP zones in Al-Ag alloys were investigated by high-resolution transmission electron microscopy (HRTEM). GP zones had facets and parcentage of faceting in GP zones decreased with increasing mean diameters rather than increaing aging temperature. We found out the concentration gradient of silver near the interface between GP zone and the matrix. This Ag-concentration gradient, moreover, depends on size of GP zones, namely, small GP zones have higher gradients, while larger GP zones have lower gradients. This tendency has been also confirmed by silver-maps by EFTEM.