Preheat your oven to 350°F (175°C). Grease a loaf pan.
In a large bowl, whisk together the flour, sugar, baking soda, cinnamon, and salt.
In another bowl, combine the grated zucchini, grated apple, vegetable oil, beaten eggs, and vanilla extract.
Add the wet ingredients to the dry ingredients and stir until just combined.
Pour the batter into the prepared loaf pan.
Bake for 60 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.