Background: A commercial preparation of recombinant human chorionic gonadotrophin (r-hCG, Ovitrelle*) was launched in 2001. Generally, hCG is available in two formats: human chorionic gonadotrophin (u-hCG), derived from the urine of pregnant females, and r-hCG produced by DNA based biotechnology. Method: The analytical characteristics of a highly purified u-hCG (Gonasi HP dagger) were assessed and compared, for the first time, with the recombinant derived r-hCG (Ovitrelle). Gonasi HP is produced by extracting and purifying hCG from urine to obtain a specific bioactivity of 5000IU/mg protein. Ovitrelle is produced via a recombinant derived mammalian cell line and purified to obtain a specific activity of 26000IU/mg. Results and conclusion: It has been documented that commercially available u-hCG preparations can contain a number of urine derived protein contaminants as well as hCG related metabolites. This is also the case for Gonasi HP, where hCG related molecules and other proteins were found to be present, including epidermal growth factor (EGF) and eosinophil derived neurotoxin (EDN). It was also demonstrated that this preparation contained high levels of oxidised hCG. r-hCG was confirmed to be essentially intact hCG, free from contaminant proteins and with very low levels of oxidised hCG.