Resonant tunneling of double-barrier quantum wells (DBQWs) affected by interface roughness has been investigated. Our results show that interface roughness induces oscillation resonant structure around the principal resonant peak. Effects of interface roughness on the resonant bias voltage, peak-to-valley current ratio, and the width of the principal resonant peak are also investigated. Temperature effect is discussed. The results obtained here may be used to explain the oscillation or intrinsic instability observed in DBQW resonant-tunneling structures.