The invention provides liquid formulations containing buprenorphine, a pharmaceutically acceptable salt thereof, or a derivative thereof. The invention further provides liquid formulations containing buprenorphine and naloxone, pharmaceutically acceptable salts thereof or derivatives thereof. The invention further provides a method of treating pain or opioid dependence by administering liquid formulations containing buprenorphine or a combination of buprenorphine and naloxone, a pharmaceutically acceptable salt thereof, or a derivative thereof to a patient in need thereof.