Maternal malnutrition results in learning deficits and predisposition to anxiety and depression in the offspring that extend into adulthood. At the cellular level, learning and memory rely on the production of new neurons in the dentate gyrus (DG) of the hippocampus, and hippocampal neurogenesis has been associated with the etiology and treatment of depression, but whether adult neurogenesis is affected by malnutrition during early life is not known. To investigate the effects of perinatal undernutrition on neurogenesis at adulthood, pregnant Sprague Dawley rats were fed either ad libitum (C) or were undernourished by reducing their daily food intake by 50% in relation to the C group during gestation and lactation (FR/FR). At birth, one subset of control pups was cross-fostered to food-restricted dams to constitute a third group of animals that were undernourished during the lactation period only (AdLib/FR). At 90 days of age, pups were injected with bromodeoxyuridine (BrdU) and sacrificed 2 h, week, or 3 weeks later. The number of BrdU-labeled cells in the DG was significantly reduced in the offspring of FR/FR dams in relation to controls at all the time points examined. However, the proportion of new cells exhibiting a neuronal phenotype was higher in FR/FR rats than in controls as revealed by the colabeling at 3 weeks of the BrdU-labeled cells with neuron-specific nuclear protein (NeuN). AdLib/FR animals exhibited also reduced BrdU labeling at 2 h and 1 week. Nevertheless, we found no significant differences at 3 weeks in either the number of BrdU-labeled cells or in the proportion of new neurons between controls and AdLib/FR rats. These results indicate that the decreased number of hippocampal neurons in perinatally undernourished rats is due to the deleterious effects of early nutrient restriction on cell proliferation but not on the neuronal differentiation process of the new generated cells.