A high fat diet during pregnancy or lactation has been linked to a dramatic rise in type II diabetes, metabolic syndrome and cardiovascular disease in adult offspring. We have previously reported that high-fat diet increases susceptibility and severity of ischemic stroke in adult Sprague-Dawley (SD) rats. In the present study, we investigated the relative effects of high-fat feeding during 1) pregnancy and 2) lactation period on the severity of ischemic stroke in adult offspring. Female SD rats were exposed to either high fat diet(HF) or control(C) diets 10 days before and throughout pregnancy. Half of the pups were cross fostered to dams consuming different diet during lactation period. From weaning, all offspring were fed a balanced diet and received middle cerebral artery occlusion at 6-month-old. Male offspring of fat-fed dams during pregnancy and suckling (HF/HF) demonstrated increased functional impairments in both the staircase and beam-traversing tests, as well as increased volume of infarction compared with controls (C/C). Male offspring of fat-fed dams cross fostered to dams consuming the control diet during suckling (HF/C) also had worse behavioral or histological assessments. Similarly, male offspring of control diet-fed dams cross fostered to dams consuming a fat diet (C/HF) had more serious functional and histological impairment. The results of this study demonstrate as one kind of distress in early life, high-fat feeding through either pregnancy or lactation worsen the outcomes of ischemic stroke in adult offspring.