In this study, physiological, anatomical and cytogenetic effects 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 and anatomical damages were investigated in root tip cross sect ions. To determine the toxicity, a control and three treatment groups were formed and the treatment groups were germinated with 50, 100 and 2(X) mg L-1 Pb(NO3)(2) at 25 degrees C for 72 hours. The results indicated that Pb(NO3)(2) application 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 fragment. sticky chromosome, chromosome bridge and c-mitosis. In addition, Pb(NO3)(2) application caused the anatomic damages including cortex cell wall thickening, cell deformation, nonspecific transmission tissue. necrosis in A. cepa root cells. As a result, Pb(NO3)(2), was found to cause toxicity depending the application dose and it was determined that A. cepa was a strong bioindicator in determining the toxicity.