A chemiluminescence (CL) immunoassay was developed to determine human growth hormone (hGH) based on copper-enhanced gold nanoparticles. In this method, gold nanoparticles were deposited on polystyrene wells for adsorption of human growth antibodies as well as catalyst for reducing of copper ions from the copper enhancer solution. The reduction of copper ions was prevented where the gold nanoparticles were covered by the antibody–antigen immunocomplex. The deposited copper on Au nanoparticles was then dissolved in HNO₃ solution and quantified using the CL method. The CL intensity response was logarithmically dependent on the hGH concentrations over the range 0.2–50 ng/mL, with a detection limit (3σ) of 0.036 ng/mL. Copyright © 2012 John Wiley & Sons, Ltd.