Abstract The essential oil from the aerial parts of Nepeta rtanjensis Diklic et Milojevic, Lamiaceae was obtained by steam distillation of the herb, collected in full blooming stage, with an average yield of 0.3%. Nineteen constituents (95-0% of the total oil) were identified by mass spectrometry. The principal one was 4aα,7α,7aβ-nepetalac-tone (86.4%), along with 2-methoxy-p-cresol (1.5%), α-pinene (1.4%) and 1,4-dimethyl-benzene (1.0%). All the others were present in quantities below 1%.