Chemical composition of the essential oils of Cistus libanotis from eastern Morocco (Tafoughalt and Jerrada) extracted from different season was analyzed by GC-MS and GC-FID. The hydro-distilled essential oil content ranged from 0, 27 % to 0, 46%, the maximum amounts were observed in summer while minimum in winter for Tafoughalt, whereas the oil obtained from Jerrada had the highest yield (0, 61 %). The essential oils consisted of terpineol-4 as the most abundant component (18, 70 % - 24, 91 %), followed by γ-terpinene (9, 82 % - 12, 25 %), camphene (5, 86 % - 13, 58 %), sabinene (7, 86 % - 9, 89 %) and α-thujene (6, 92 % - 10, 12 %). Samples collected in all seasons were found to be richer in monoterpenes hydrocarbons (52, 68 % - 57, 59 %). None sesquiterpene hydrocarbons found in the oils from summer and autumn. Drying period of leaves at normal air laboratory and distillation time also affect the oil content and composition. There was variation in terpineol-4 content from 22, 23 % (4th day of drying) to 19, 27 % (29th day of drying), and from 35, 60 % (1 hour of distillation) to 24, 17 % (4 hours of distillation). It can be concluded that the harvesting season, period of drying and the time of distillation had an effect on the yield of essential oil and chemical composition of various compounds.