Investigations of bound pesticide residues carried out to date involved the detection of residues in commodities, their identification, determination, bioavailability and possible biological effects. The results obtained in this research and the results of other authors who have shown an increasing concern about the levels, bioavailability and biological effects of bound pesticide residues since the late 1980' are presented in this paper. Based on the results obtained, bound pesticide residues were detected in some commodities ranging from trace amounts to over 50% of the dose level applied. The residue content was influenced by the biochemical structure of the commodity, the compound and its application rate, the length of time from the application to residue analysis as well as on some environmental parameters (primarily temperature and humidity). It was also established that the bioavailability to experimental animals may range from medium to significant provoking adverse biological effects. These effects depended on the compound, its application rate and length of administration. Based on the results obtained so far it was established that bound pesticide residues need to be taken into account when determining maximum residue limits (MRL) as well as when assessing the toxicological risks of pesticide application.