Preheat the oven to 375 degrees F (190 degrees C). Grease cookie sheets.
In a medium bowl, cream together the margarine, white sugar and brown sugar until smooth. Beat in the eggs one at a time, then stir in the vanilla. Sift in the flour, baking soda, salt and cocoa powder; mix well. Stir in the chocolate chips. Roll tablespoonfuls of dough into balls and place them one inch apart onto the prepared cookie sheets.
Bake for 8 to 10 minutes in the preheated oven. Allow cookies to cool on baking sheet for 2 minutes before removing to a wire rack to cool completely.