Preheat oven to 350 degrees F (180 degrees C).
Mix together flour, cocoa, baking soda and salt. Cream margarine, both sugars, and vanilla until creamy. Beat in eggs 1 at a time, beating 11/2 minutes after each addition. Beat in the flour mixture. Stir in the chocolate chips.
Drop by tablespoon onto ungreased cookie sheets. Bake for 8 to 10 minutes or until puffy. Centers will be soft. Let stand on cookie sheets for 2 minutes, then remove to wire racks to cool completely.