Nuveen Municipal High Income Opp Fund is a diversified, closed-end management investment company. The company's investment objectives is to provide current income exempt from regular federal income tax by investing predominantly in a portfolio of municipal obligations issued by state and local government authorities or certain U.S. territories. It seeks to provide attractive monthly tax-free income, portfolio diversification and attractive after tax total returns. The fund invests in municipal securities that are exempt from federal income taxes.