Abstract Essential oils from the leaves of Thymus vulgaris L. collected from Caxias do Sul (Rio Grande do Sul State, Brazil) were isolated by hydrodistillation with an average oil yield of 0.25%. Twenty-two components were identified by GC and GC/MS analysis. Thymol was found to be the most abundant constituent (31.5â52.4%), followed by p-cymene (17.1â34.4%). Thyme possessed a higher oil yield and the oil was richer in oxygenated compounds when harvested in the spring.