the essential oil composition of lemon balm (melissa officinalis l.) produced in two ecological conditions were evaluated using gas chromatography-flame ionization detector (gc-fid) and gc-mass spectrometry (gc-ms). thirty-three constituents, representing 91.4 +/- 1.56% to 98.1 +/- 0.60% of the total oil compositions, were identified. the major constituents of the essential oil were geranial (42.3 +/- 1.77% to 44.9 +/- 3.23%), neral (30.7 +/- 1.11% to 32.6 +/- 3.57%), (e)-caryophyllene (2.8 +/- 1.00% to 3.5 +/- 1.27%), geranyl acetate (0.7 +/- 0.49% to 3.3 +/- 0.15%), geraniol (0.9 +/- 0.93% to 2.6 +/- 0.35%), piperitone (0.6 +/- 0.96% to 2.5 +/- 1.81%), nerol (0.8 +/- 0.44% to 2.4 +/- 0.23%), caryophyllene oxide (0.8 +/- 0.81% to 2.3 +/- 0.55%), (e)-isocitral (0.5 +/- 0.06% to 2.1 +/- 0.46%) and citronellal (0.4 +/- 0.52% to 2.1 +/- 0.06%). the examined lemon balm essential oil was considerably rich in monoterpenoid aldehyde (citral, 73.0-77.5%).