Faecal analysis has proven to be a useful method of studying the diets of wild apes. This is especially true for populations living in tropical forest habitat in central Africa where dense vegetation makes systematic observation of feeding difficult. The method developed and used for faecal analysis in the Lopé Reserve, Gabon, where gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglodytes) co-occur, are described and some examples given of some of the ways in which data can be qualified and analised. Faecal analysis alone cannot give a complete picture of diet as some foods leave no recognisable remains and others, particularly vegetative plant parts, are difficult to identify taxonomically. However, standard application of the methods allow some comparisons to be made between years, species and sites.