The present invention relates to monoclonal antibodies that specifically bind buprenorphine and/or at least one metabolic product thereof. The present invention further relates to buprenorphine metabolite conjugates for the production of monoclonal antibodies that specifically bind buprenorphine and/or at least one metabolic product thereof and hybridoma cells that produce the monoclonal antibodies. The invention also relates to immunoassay methods for determining buprenorphine and/or one or more buprenorphine metabolites in a sample using the novel antibodies and conjugates of the present invention.