abstract forty compounds have been characterized by gc and gc/ms and relative retention times in 300 samples of niaouli (melaleuca quinquenervia) oils collected on 75 different trees during four seasons. twenty-one compounds were submitted to multivariate statistical analyses using principal component analysis (pca). factorial discriminant analysis (fda) revealed the presence of three chemotypes. chemotype i is already known (1,8-cineole; 50%), chemo-type ii had an equal content in 1,8-cineole (33%) and viridiflorol (32%). the third (chemotype iii) was characterized by a high content in viridiflorol (50%). the 1,8-cineole chemotype represented 58% of three populations. seasonal differentiation does not occur, showing that niaouli oil composition is stable all year.