Abstract Hortia oreadica Groppo, Kallunki & Pirani, Rutaceae, known as “para-tudo”, “quina”, and “quina-do-campo”, is used in traditional medicine locally to treat stomach pain and fevers. The aims of this study were: analyze the chemical composition of essential oils from leaves, flowers and fruits of H. oreadica and verify the seasonal variation of the chemical components of essential oils from leaves. The essential oils were obtained by hydrodistillation using a Clevenger type apparatus and analyzed by GC/MS. The major components found in the samples of the essential oils were the amorpha-4,7(11)-diene (29.27% – flowers, 20.26% – fruits, 27.66–37.89% – leaves), bicyclogermacrene (23.28% – flowers, 20.64% – fruits, 14.71% to 31.37% – leaves). This work represents the first study of the chemical composition of essential oils from leaves, flowers and fruits and seasonal variation in the essential oils from leaves of H. oreadica.