Seven essential oils were tested for in vitro cytotoxicity against the cancerous cell lines A-549, HEp-2 and DLA and normal BRL-3A, NRK-49F and Vero cell lines using standard MTT, SRB and dye exclusion techniques. The A-549 cell line was found to be the most susceptible to all the essential oils. The essential oils of A. nilagirica, A. calamus and O. sanctum were found to be the more active against these cells with mean $CTC_{50}$ values of 17.75, 19.00 and $24.37;{mu}g/ml$, respectively. The essential oil of Acorus calamus was found to be the most potent with low $CTC_{50}$ values against the cancerous and comparatively higher $CTC_{50}$ values against the normal cell lines. Artemisia pellens and Pelargonium graveolens oils also showed potent activity. These oils merit further investigation to identify the active principles and nature of the anti tumor activity in animal models.