An open, randomized clinical study was performed by evaluate the efficacy of diflunisal versus acetaminophen with codeine in patients who underwent outpatient arthroscopy of the knee. Twenty patients were randomly assigned to each treatment group. Nineteen patients in each group successfully completed the study, which consisted of both objective and subjective evaluations. The results showed equal efficacy between the two drugs. However, a larger percentage of patients viewed diflunisal as providing good to excellent results overall compared with acetaminophen with codeine.