The purpose of this research is to investigate the behavior of non-ductile reinforced concrete (RC) frames strengthened by introducing partial infills under cyclic lateral loading. Seven one-bay, two-story, 1/3-scale test specimens were constructed and tested. The test frames had deficiencies commonly observed in residential RC buildings in Turkey. The aspect ratio of the infilled wall (l(w)/h(w), where l(w) = infill length and h(w) = infill height) and its placement configurations were the parameters of the experimental study. Test results revealed that partially infilled nonductile RC frames exhibited significantly higher ultimate strength and higher initial stiffness than the bare frame (frame with no infill). As the aspect-ratio of the infilled wall increased the lateral strength and the rigidity significantly increased. Strength and ductility inadequacies of. the frame members influenced the lateral performance of the frame strengthened by partial infills. The most successful behavior was obtained from specimens with partially infilled walls connected to both the columns and beams of the frame.