Basic information on neutron activation analysis (NAA) and its application in environmental studies is presented. The fundamentals of the technique are shown while various methods of neutron activation analysis are briefly characterized in order to depict the most important information. A rich set of NAA applications for human and biological samples is given together with the short description of the results. The problems associated with the quality assurance and control are also pointed out and discussed. The information is addressed to researchers interested in the applications of neutron activation analysis or to those who are searching for a suitable alternative analytical technique for environmental studies on human and other biological samples, where other techniques are not the best choice.