The effects of developmental lead (Pb²⁺) exposure on the anxiolytic-like effect of diazepam (5.0 mg/kg IP) and 8-OH-DPAT (0.3 mg/kg IP) were studied. Wistar dams were exposed to 250 ppm lead acetate in drinking water during pregnancy. Control rats were derived from dams that consumed tap water, and had no exposure to Pb²⁺ afterwards. Male offspring were tested at the age of 12 weeks. We studied the anxiolytic-like effect of diazepam and 8-OH-DPAT in an elevated plus maze device and the Vogel conflict test. Diazepam in doses of 5.0 mg/kg IP significantly increased the percentage of time spent on open arms in control rats being without effect in Pb²⁺-exposed animals. 8-OH-DPAT 0.3 mg/kg IP increased the percentage of time spent on open arms in both experimental groups (control and Pb²⁺), but the anxiolytic-like effect was much more pronounced in Pb²⁺-intoxicated animals. The benzodiazepine anxiolytic diazepam produced a significant effect in the Vogel conflict test in control rats. A 5.0 mg/kg dose of those drugs caused a significant increase in the number of electric shocks rats received. In the ontogenetically Pb²⁺-exposed rats diazepam also augmented the number of shocks accepted, but this effect was much less pronounced than in control animals. Conversely, 8-OH-DPAT at doses of 0.3 mg/kg IP was without effect in both tested groups as far as the anticonflict effect is concerned. The results of the present report demonstrated that exposure to Pb²⁺ during pregnancy induced hypersensitivity to 5-HT_1A agonist mediated anxiolytic-like effect but attenuated that of benzodiazepine (diazepam).