Abstract Abstract The effect of planting practice (at sun and in the shade) and harvest time on the oil yield and its composition was assessed in Melissa officinalis L. cultivated in Cuba. The oil yield ranged from 0.3 to 0.5 ml/100 g dry basis and was higher in the plant cultivated at sun and collected in Apr. Comparative determinations of the oil yield of plant material collected at different times of the day showed no significantly difference between them. The analysis of the essential oil composition was performed by GC and GC-MS. No great differences in the contents of neral, geranial, and other minor compounds among the populations were found. Key words: Melissa officinalislemon balmessential oil