In this study, physiological, anatomical and cytogenetic effects of different doses of Pb(NO3)2 in Allium cepa L. were investigated. The root length, percentage of germination and weight increase were used as physiological parameters and chromosomal damage frequency, mitotic index (MI) and micronucleus (MN) frequency were determined as cytogenetic parameters. The anatomical damages were investigated by examining the root tip cross sections of the plant. To determine the toxicity, a control and three administration groups were formed and the treatment groups were germinated with 50, 100 and 200 mg of L-1Pb(NO3)2 at 25°C for 72 hours. The result of experiment indicated that Pb(NO3)2application decreased the germination percentage, root length, weight gain and MI, and increased the MN frequency and chromosomal damage formations. It was observed that Pb(NO3)2 induced chromosomal damages such as the unequal distribution of chromatin, fragment, sticky chromosome, chromosome bridge and c-mitosis. In addition, Pb(NO3)2application caused the anatomic damages including cortex cell wall thickening, cell deformation, nonspecific transmission tissue, necrosis, accumulation of some substances in the cortex cells and flattened cell nucleus in A. cepa root end meristematic cells. As a result, Pb(NO3)2 was found to cause physiological, anatomical and cytogenetic toxicity depending the application dose and it was determined that A. cepa was a strong bioindicator in determining the toxicity.