<p>Seismic performance assessment of a RC frame building was conducted for original and strengthened states to investigate the effectiveness of strengthening technique of infill walls by carbon fiber reinforced polymer (CFRP). Structural model representing CFRP strengthened infill wall was based on the previous experimental work of the author. In the first part of this paper, the experimental work was explained briefly, details of strengthening technique and proposed structural model were given. In the second part, nonlinear time history analyses of a RC frame building were performed for original and strengthened states. Maximum interstory drift ratios obtained from nonlinear time history analysis were used to derive cumulative density functions and a comparison was made in terms of probability of exceedance curves of original and strengthened buildings. It was concluded that strengthening of selected infill walls by CFRP as proposed in this study clearly improved seismic behavior of the structure and that improvement was quantified with cumulative density functions.</p>