Preheat oven to 350 degrees F (175 degrees C). Combine the flour, oats, baking soda, cinnamon and salt; set aside.
In a large bowl, cream together the butter, brown sugar and white sugar until smooth. Beat in the egg and vanilla then stir in the pumpkin puree. Gradually stir in the dry ingredients until well blended. Mix in raisins. Drop by rounded spoonfuls onto ungreased cookie sheets.
Bake for 8 to 10 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes before removing to a wire rack to cool completely.