Preheat oven to 350 degrees.
In a double boiler melt chocolate and margarine. Let cool slightly. Beat eggs lightly in medium bowl. Add sugar, corn syrup, chocolate mixture, and vanilla; stir until well blended. Mix in pecans.
Set pie shell on heavy-duty baking sheet and pour in filling. Bake 50 to 55 minutes, until knife inserted midway between center and rim comes out clean.
Cool pie on wire rack to room temperature before cutting.