In a 9x13-inch baking dish, combine the pretzels and nuts. Set aside.
In a large saucepan combine the butter, sugar, corn syrup and salt. Stir together over medium heat until sugar dissolves. Bring to a boil and cook until very thick and at the 'firm ball' stage (260 degrees F, 125 degrees C). Remove from heat, pour over pretzel/nut mixture and mix all together.
Bake in the preheated oven for 20 minutes, stirring after 10 minutes. Remove from oven and spread out on wax paper to cool.