High performance liquid chromatography (HPLC) has been optimised for the analysis of the creatine content and possible organic contaminants in 33 samples of creatine supplements from the market. Creatinine resulted to be the major organic contaminant (44% of the samples over 100 mg/kg). About 15% of the samples had dihydro-1,3,5-triazine concentrations exceeding the detection limit of 4.5 mg/kg (maximum 8.0 mg/kg) and a dicyandiamide concentration over 50 mg/kg, while none of the samples were contaminated with thiourea. The heavy metals (arsenic, cadmium, mercury and lead) content was also assessed by means of inductively coupled plasma mass spectrometry (ICP-MS). Only mercury was present in detectable amounts (at levels lower than 1 mg/kg).