Indoor Radon Research and Assistance Act of 1986 - Amends the Environmental Research, Development, and Demonstration Authorization Act of 1981 to direct the Administrator of the Environmental Protection Agency to establish a research and development program concerning environmental and human health effects posed by radon through indoor accumulation and to complete within one year a nationwide survey on the sources and levels of radon. Requires coordination with other Federal programs and technical assistance to the States as well as other research and information clearinghouse activities. Requires the Administrator to report annually to the Congress on such program. Authorizes appropriations for FY 1987 through 1991.