Soak poppy seeds in milk for 2 hours. Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 10 inch Bundt pan.
In a large bowl, stir together cake mix and pudding mix. Make a well in the center and pour in water, oil, and eggs. Beat on low speed until blended. Scrape bowl, and beat 4 minutes on medium speed. Blend in poppy seed mixture. Pour batter into prepared pan.
Bake in the preheated oven for 60 minutes, or until a toothpick inserted into the center of the cake comes out clean. Let cool in pan for 10 minutes, then turn out onto a wire rack and cool completely.