Lycium　barbarum　(Fructus　Lycii,　Wolfberry,　or　Gouqi)　belongs　to　the　Solanaceae.　The　red-colored　fruits　of　L.　barbarum　have　been　used　for　a　long　time　as　an　ingredient　in　Chinese　cuisine　and　brewing,　and　also　in　traditional　Chinese　herbal　medicine　for　improving　health.　However,　its　effects　on　cognitive　function　have　not　been　well　studied.　In　the　present　study,　prevention　of　a　milk-based　wolfberry　preparation　(WP)　on　cognitive　dysfunction　was　tested　in　a　prenatal　stress　model　with　rats　and　the　antioxidant　mechanism　was　tested　by　in　vitro　experiments.　We　found　that　prenatal　stress　caused　a　significant　decrease　in　cognitive　function　(Morris　water　maze　test)　in　female　offspring.　Pretreatment　of　the　mother　rats　with　WP　significantly　prevented　the　prenatal　stress-induced　cognitive　dysfunction.　In　vitro　studies　showed　that　WP　dose-dependently　scavenged　hydroxyl　and　superoxide　radicals　(determined　by　an　electron　spin　resonance　spectrometric　assay),　and　inhibited　FeCl(2)/ascorbic　acid-induced　dysfunction　in　brain　tissue　and　tissue　mitochondria,　including　increases　in　reactive　oxygen　species　and　lipid　peroxidation　and　decreases　in　the　activities　of　complex　I,　complex　II,　and　glutamate　cysteine　ligase.　These　results　suggest　that　dietary　supplementation　with　WP　may　be　an　effective　strategy　for　preventing　the　brain　oxidative　mitochondrial　damage　and　cognitive　dysfunction　associated　with　prenatal　stress.