Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 10 inch Bundt pan.

In a large bowl, mix flour, sugar, baking soda, salt and cinnamon. Make a well in the center and pour in the eggs, oil, vanilla, pineapple, mashed banana and chopped walnuts. Mix well and pour into prepared pan.

Bake in the preheated oven for 75 minutes, or until a toothpick inserted into the center of the cake comes out clean. Serve hot or cold.