Migration of antidegradants to the surface in silica-filled natural rubber (NR) vulcanizates was studied with migration-generating equipment using a vacuum technique. 2,6-Di-t-butyl-4-methyl phenol(BHT), N-phenyl-N＇-isopropyl-p-phenylenediamine(IPPD), N-phenyl-N＇-(1,3-dimethylbutyl-p-phenylenediamine(HPPD)), and wax (n-C23H48, n-C24H50, n-C25H52, and n-C26H54) were employed as antidegradants. The migration rate was found to be dependent on the content of silica in the vulcanizates. IPPD migrates faster than BHT and HPPD irrespective of the content of silica, BHT migrates faster than HPPD at 60 and 80 degrees C, but slower than HPPD at 100 degrees C. The migration rates of BHT, IPPD, and HPPD decrease with increase of the silica content from 30 to 70 phr. Wax with a low molecular weight migrates faster than that with a high molecular weight. The migration rate of n-C23H48, irrespective of migration temperature, decreases with increase of the silica content, similar to BHT, IPPD, and HPPD, but those of n-C25H52 and n-C26H54 have a local maximum at 50 phr silica content. The activation energies for migration to the surface in the vulcanizate containing 50 phr of silica are 19.3, 28.7, 40.1, 42.2, 51.6, 58.8, and 65.5 kJ/mol for BHT, IPPD, HPPD, n-C23H48, n-C24H50, n-C25H52, and n-C26H54, respectively.