Low-density polyethylene (LDPE) modified asphalts with improved high-temperature storage stability are prepared by incorporating silica into the LDPE compounds. The effect of silica on the high-temperature Storage stabilities, dynamic rheological and mechanical properties, and morphologies of the modified asphalts are studied. It is found that the LDPE/silica ratio in the compound has a great effect on the high-temperature storage stability. The modified asphalts are stable when the ratio of LDPE/silica is around 100/60 (w/w). The silica content in the modified asphalts is less than 3.2%, and it has a slight influence on the mechanical properties of the modified asphalts. Silica can improve the rheological properties of the modified asphalt to some extent. The high-temperature storage stability can be increased by a decreasing density difference between the LDPE/silica compound and the asphalt or in terms of equalizing the polarity differences between asphalt and LDPE by silica. (c) 2006 Wiley Periodicals, Inc.