Four steroid hormones namely androsterone, cholesterol, estrone and estradiol have been pyrolysed at 300, 400 and 500 o C and the pyrolysates from these have been analysed by GC-MS.The results indicate that these formed different products under the pyrolysis and most of them evolved into polycyclic aromatic hydrocarbons during their residence in the pyrolysis chamber at high temperatures. The products from the pyrolysates at all temperatures have been analysed for similarities and differences using multivariate data analysis. The products possessed some similarities on pyrolysis at 300 o C but were entirely different when pyrolysed at 500 o C.Androsterone and cholesterol formed a higher percentage of substituted PAH than estrone and estradiol. These compounds included carcinogens such as phenanthrene, methylphenanthrene, fluorene and its derivatives. The side chain of cholesterol had no effect on the products formed, while the presence of the aromatic ring in estrone and estradiol led to a higher percentage of phenol and its derivatives in the pyrolysates. Furthermore, estrone has been subjected to flash pyrolysis and the products formed have been compared with those which resulted from the long time pyrolysis: flash pyrolysis produced small amounts of PAH. * Corresponding author.2