A new lookahead instruction prefetching mechanism is proposed in this paper. Though significant performance improvement can be obtained by improving both the cache miss ratio and average access time for successfully prefetched blocks, most conventional prefetching mechanisms improve only one out of the two factors. To achieve balanced improvement of the two factors, a lookahead prefetching scheme that fetches multiple blocks for a prefetch request and adopts prefetch on miss mechanism is proposed. Performance evaluation is carried out through the trace-driven simulation and the proposed prefetch scheme reduces 32%/spl sim/56% of the memory access delay time of the cache system that does not perform any prefetching.