The　effects　of　annealing　on　microstructure,　magnetoresistance,　and　hardness　of　an　in　situ　Cu-Nb　microcomposite　wire　have　been　investigated.　Neither　changes　in　microstructure　nor　hardness　were　found　until　500　degrees　C.　Particularly,　microstructural　change　within　the　Nb　films　was　observed　in　the　annealed　samples.　The　room-temperature　magnetoresistivity　was　almost　negligible,　while　magnetoresistivity　at　-196　degrees　C　increased　with　magnetic　field.　At　temperature　above　500　degrees　C,　recovery　and　recrystallization　occurred,　and　both　the　resistance　and　hardness　decreased.