In a group of office workers (bookkeepers) that were within 2 months (October-December 2013) under the influence of LED lighting with levels of 300-400 lx in the horizontal plane, the con-tent of melatonin metabolite – 6-sulfatoxymelatonin in the urine was higher than in the control group (office workers, with the standard fluorescent lighting) at the beginning of the work week (in the morning – by 16.9% during the day – 44.2%), and especially at the end of the working week (in the morning – by 31.7%, in the afternoon – 66,4%). Such changes are indicative of the absence of the negative impact of LED lighting on melatonin metabolism in the human body in terms of the occupa-tional study for 2 months.