The essential oils obtained by water distillation from the aerial parts of Helichrysum italicum G. Don subsp. microphyllum (Willd.) Nym. were analyzed by GC and GC/MS. Three different populations growing at different elevations and under different weather conditions were studied from their vegetative period to post-blooming time. Forty-eight constituents accounting for between 96.5% and 83.0% of total oils have been identified and quantified. Among the identified constituents those present in the highest percentage were neryl acetate (17.6-35.6%), nerol (3.7-14.4%) and eudesmen-5-en-11-ol (6.4-23.5%). Among them, the neryl acetal percentage decreased when 5-eudesmen-11-ol percentage increased, and limonene reached 7% relative composition. The main fraction of the oil consisted of oxygenated compounds present in higher concentrations in June. © 2010 Allured Business Media.