BlackRock Muni Intermediate Duration Fund, Inc. (the Fund) is a non-diversified, closed-end management investment company. The Fund's objective is to provide common shareholders with high current income exempt from federal income taxes. The Fund seeks to achieve its investment objective by investing at least 80% of its assets in municipal bonds exempt from federal income taxes (except that the interest may be subject to the federal alternative minimum tax).The Fund may invest directly in such securities or synthetically through the use of derivatives. Under normal market conditions, the Fund invests at least 75% of its assets in municipal bonds rated investment grade and invests at least 80% of its assets in municipal bonds with duration of 3 to 10 years at the time of investment. The Fund�s investment advisor is BlackRock Advisors, LLC. The Fund�s sub-advisor is BlackRock Investment Management, LLC.