Throughout human history, plant products have been used for many purposes including as medicines. Herbalproducts and spices can be used as preventive agents against cancer due to their antimicrobial, antioxidant andantitumorigenic properties. This study was designed to evaluate the potential protective effect of curcum in ratsadministered nitrosamine precursors; dibutylamine (DBA) and sodium nitrate (NaNO3); and infected withEscherichia coli (E. coli) and also to monitor changes in nuclear factor the Kappa B p65 (NF-κB p56) pathwayand its downstream products, Bcl-2 and interleukin-6 (IL-6), in parallel with nitrosamine precursors, E. coliand curcum treatment. Rats were divided into three groups (n=25 each; except of control group, n+20). GroupI a normal control group, group II administered DBA/NaNO3 in drinking water and infected with E. coli andgroup III was administered DBA/NaNO3 in drinking water, infected with E. coli and receiving standard dietcontaining 1% curcum powder. Histopathological examination reflected that the curcum treated group featureda lower incidence of urinary bladder lesions,and lower levels of NF-κB, Bcl-2 and IL-6, than the group receivingnitrosamine precursor and infected with E. coli. These findings suggested that curcum may have a protective roleduring the process of bladder carcinogenesis by inhibiting the NF-κB pathway and its downstream products.