PURPOSE:To translate, culturally adapt, evaluate the measurement properties, and propose a new scoring system of the Cincinnati Knee Rating System for the Brazilian population. MATERIALS AND METHODS:One hundred fifty people with anterior cruciate ligament injury completed Cincinnati Knee Rating System and Lysholm Knee Scoring Scale on three occasions: 1-week prior to surgery, 90-days after and 95-days after reconstruction. The measurement properties of the Brazilian-Portuguese Cincinnati Knee Rating System, internal consistency, construct validity, reproducibility, ceiling and floor effect and responsiveness, were tested. RESULTS:Using the original scoring system (multiple scores), the internal consistency (Cronbach's α) varied between 0.54-0.79 (if item deleted = 0.07-0.73); the construct validity (Pearson's r) varied between 0.19-0.82 (related to Lysholm); the reliability (intraclass correlation coefficient) varied between 0.96-0.99; the standard error of measurement varied between 0.2-1.3 points; the minimum detectable change varied between 0.4-3.5 points; no ceiling or floor effect was detected, and responsiveness (effect size) varied between -0.3-2.7. Using the new proposed scoring system (single score), Cronbach's α was 0.78 (if item deleted = 0.65-0.71); the Pearson's r was 0.79 (related to Lysholm); the intraclass correlation coefficient was 0.99; the standard error of measurement was 0.5 points, the minimum detectable change was 1.3 points; no ceiling or floor effect was detected, and effect size was 1.4. CONCLUSIONS:The Brazilian-Portuguese Cincinnati Knee Rating System has adequate property measurement and can be used in a Brazilian population. The new proposed scoring system is appropriate. Implications for rehabilitation The Brazilian-Portuguese Cincinnati Knee Rating System is a valid and reliable instrument which can identify consistent clinical changes over the time. The Brazilian-Portuguese Cincinnati Knee Rating System can be used to evaluate and to follow-up a Brazilian population with anterior cruciate ligament injuries and postoperative reconstruction. The new proposed score for Cincinnati Knee Rating System is appropriate and did not compromise the quality of the measurement properties. The new scoring system generates a unique score, creating a potentially simpler and faster clinical understanding of the patient's condition.