Abstract: The aim of this study was to evaluate the effects of different doses of dietary soy meals (with or without isoflavone) on dementia in ovariectomized (OVX) animal model of Alzheimer`s disease. Female Wistar`s rats with the exception of intact group were ovariectomized at the first line of study. Animals were divided into 2 main groups: control (c) and pre-treatment groups. Animals in pre-treatment groups received one of five types of diet during four weeks prior Nucleus Basalis Magnocellularis (NBM) electrical lesion normal diet (0), 10 g soy with isoflavone (10), 20 g soy with isoflavone (20), 10 g soy without isoflavone (-10) and 20 g soy without isoflavone (-20) in 30 g daily diet. The spatial learning and memory were tested using Morris water maze after electrical lesion. Rats were trained in water maze to find a hidden escape Platform. Rats received 6 blocks that each block consisted of 3 trials. Following acquisition trials, one probe trial was conducted in which the platform was removed. Soy meal diet (with or without isoflavone) in ovariectomized rats with Alzheimer`s disease caused improvement of performance across 18 trials of Acquisition. Our results suggest that soy meal is a potential alternative to estrogen in the prevention and treatment of Alzheimer`s disease.