The present study considered a possible way of classifying fossil and sub-fossil resins by means of thermal analysis, by using thermogravimetric (TG) and differential thermogravimetric (DTG) profiles. We used samples of resins of different origin and ages. ranging from present-day to Triassic (225 million years ago (Ma)), in order to extend the knowledge of thermal patterns of very ancient resins. Under differential thermogravimetric analysis, all the samples presented a main exothermal event. whose temperature varied among resins of different age. The increasing value of the main exothermal peak varies with the increase of the age of the specimen and a significant linear correlation was found (r = 0.701, P < 0.01) with a slope of 0.216. Additional information came in relation to paleobotanical origin, lithology and diagenesis of the fossil samples.Thermal analysis of fossil resins appears therefore as a useful method that may improve the characterization of fossil resins and well correlates with the maturation grade. (C) 2003 Elsevier Science B.V. All rights reserved.