Intensification of agriculture, concentration of people in towns and cities, and growing awareness of increasing environmental pollution has resulted in the necessity to treat animal and human wastes in waste water treatment plants. However, the products of such treatment depend very much on the treated materials, system of treatment and its efficiency, and the way of recycling the products. Animal and human wastes may be a source of spreading of diseases if they are infected with causative organisms which survive the treatment (Dubinský et al., 2000, Novák, 1996, Venglovsky, et al., 2006). The hygienic risk arising from the presence of parasites and bacterial pathogens in pig slurry and sewage sludge, and in the products of biological aerobic, mesophilic waste water treatment plants treating pig slurry and municipal sludges, depends on the health status of the respective human or animal populations, and on the disposal or use of the products of treatment (Juri et al., 1992, Venglovsky et al., 2005). The aim of the study was to investigate the parasitological and bacteriological risk arising from sewage sludge and products of aerobic treatment of pig slurry and municipal sewage with regard to the recipient of the effluent and application of pre-treated sludges with or without additional treatment with quick lime and zeolite.