A large increase(∼8×)in critical current density,Jc,was achieved forin situlaser ablatedYBa2Cu3O7−&dgr;–Agfilms. High-resolution Auger electron spectroscopic investigation indicates that the Ag-doped films are stoichiometric with a relatively low grain-boundary extension (8 nm) in contrast to undopedYBa2Cu3O7−&dgr;films (32 nm). Further analysis suggests that the doped film contains a much lower silver content(<0.15 wt &percent;)than in the target material (5 wt &percent;). These observations are in excellent agreement with the temperature dependence ofJc,the room-temperature resistivity, and the surface resistance results. Thus,Jcenhancement in Ag-doped films can be attributed to their superior properties, viz., improved microstructure characteristics and the reduced resistive grain boundaries. ©1997 American Institute of Physics.