Methods, compositions and kits are disclosed directed at haptens, immunogens and immnoassays for buprenorphine (BUP) and nor buprenorphine (norBUP). The method comprises providing in combination in a medium (i) a sample suspected of containing buprenorphine (BUP) or norbuprenorphine (norBUP) and (ii) an antibody raised against an immunogen of buprenorphine (BUP) or norbuprenorphine (norBUP). The medium is examined for the presence of a complex comprising a labeled hapten of buprenorphine (BUP) or norbuprenorphine (norBUP) where the presence of such as complex indicates the presence of the compound in the sample.