The evolution of the composition of sterols and squalene during the maturation of the fruit of three cultivars (Achaak, Perlees and Mazetto) almond (Prunus amygdalus Batsh) was investigated. At the same time the evolution of oleic, linoleic and linolenic fatty acids was also studied. The qualitative and quantitative analyses were made by GC-MS and GC-FID. The present study is based on three axes: The first one is the structural and molecular identification of compounds sterolic and squalene, which are based on the principal of cleavage and the fragmentation characteristic of each peak provided by mass spectrometry. The second axis is interested in the physiological phenomenon of phytosterols accumulation: biosynthesis, evolution, and their relation with squalene as well as their interconversion. The third axis is an emergence of a relationship, which seems to exist, between the biosynthetic compounds of the glyceridic fraction of almond oil (mainly fatty acids) and those of the unsaponifiable fraction (particularly sterols). This relation may be established by 24-methylene cholesterol. To cite this article: A. Cherif et al., C. R. Biologies 332 (2009).