Lavender essential oil shows evidence of sedative properties in neurophysiological and animal studies but clinical trials of its effectiveness as a treatment of agitation in people with dementia have shown mixed results. Study methods have varied widely, however, making comparisons hazardous. To help remedy previous methodological shortcomings, we delivered high grade lavender oil in specified amounts to nursing home residents whose agitated behaviours were recorded objectively.Methods: 64 nursing home residents with frequent physically agitated behaviours were entered into a randomized, single-blind cross-over trial of dermally-applied, neurophysiologically active, high purity 30 lavender oil versus an inactive control oil. A blinded observer counted the presence or absence of target behaviours and rated participants predominant affect during each minute for 30 minutes prior to exposure and for 60 minutes afterwards.Results: Lavender oil did not prove superior to the control oil in reducing the frequency of physically agitated behaviours or in improving participants affect.Conclusions: Studies of essential oils are constrained by their variable formulations and uncertain pharmacokinetics and so optimal dosing and delivery regimens remain speculative. Notwithstanding this, topically delivered, high strength, pure lavender oil had no discernible effect on affect and behaviour in a well-defined clinical sample.