Although zinc is an essential trace element involved in many physiological functions, toxicological data concerning acute exposure are scarce. The aim of our study was to determine the maximal iterative dose of zinc that can be administrated in rats without any adverse effect. Saline (control group) or zinc gluconate at 1, 2 or 4 mg/kg were intraperitoneally injected in animals daily during 7 days. The tolerance of zinc treatments was evaluated by the observation of clinical symptoms, haematological parameters and biochemistry, in relation to the zinc and copper levels in blood, liver, pancreas and faeces. We found no serious adverse effect within 1 week in rats injected intraperitoneally with 1 or 2 mg/kg/day of zinc gluconate, which tends to indicate that those doses could be useful in future therapeutic research. In contrast, the therapeutic treatment of adult rats with repeated intraperitoneal injections of a 4 mg/kg/day zinc dose should be cancelled, due to the occurrence of clinical adverse effects within a few days, as intraperitoneal local intolerance or major growth underdevelopment.