Lead plays an important role in many industrial processes. Although highly useful to man, lead has various types of toxic effects. There is constantly growing evidence of a relationship between the induction of chromosome breaks and an increased risk of onset of cancer. However, available data about the possible genotoxic and carcinogenic action of lead are conflicting. In this report we present the results of studies on lead concentrations in blood and the respective micronucleus frequencies in peripheral blood lymphocytes from workers employed in the recycling of automotive batteries in the surroundings of Porto Alegre, Brazil. We observed that in the occupationally exposed group, both lead concentration in peripheral blood and micronucleus frequency in lymphocytes were significantly higher compared to control (Z =6.35, P <0.0001 and Z =4.47, P <0.0001). The nuclear division index (NDI) values were significantly higher in the control group than in the exposed group (Z =2.13, P =0.0330), indicating a possible effect of Pb on nuclear proliferation. We also detected a negative correlation between micronuclei and progression of nuclear division (τ =−0.312, P =0.0129). There were no changes in micronucleus frequency between smoking and non-smoking workers exposed to lead (Z =0.03, P =0.9790). The only difference found between the groups of smokers and non-smokers was with respect to NDI, whose values were significantly higher among non-smokers (Z =1.98, P =0.0481).