1. In a mixing bowl, combine rye flour, all-purpose flour, sugar, salt, and yeast.
2. Gradually add warm water and mix until a dough forms.
3. Knead the dough for about 10 minutes until smooth and elastic.
4. Place the dough in a greased bowl, cover, and let it rise for 1 hour or until doubled in size.
5. Preheat the oven to 375°F (190°C).
6. Punch down the dough, shape it into a loaf, and place it on a baking sheet.
7. Bake for 30 minutes or until the bread sounds hollow when tapped.
8. Let the bread cool on a wire rack before slicing.