A sedimentary delta(15)N record in the equatorial western Pacific (WP) shows glacial-interglacial variability from 6.2 to 11.2 parts per thousand during the last two climatic cycles, similar to the denitrification record in the eastern tropical Pacific (ETP). Contrastively, a record in the South China Sea (SCS) exhibits less changes from 4.4 to 6.4 parts per thousand and is quite alike previously published results in marginal seas in the WP. By ruling out several possible causes for the delta(15)N variability, the delta(15)N record in the equatorial WP is interpreted as the source nitrate delta(15)N signals advected from the ETP. Comparison of several delta(15)N records for the last 25 ka distributed in the WP brings out a pattern of northward decrease in delta(15)N values and variability from the equator to off Mindano and then to marginal seas, supposed to be caused by the northward increase of local N(2) fixation. Therefore, the less glacial-interglacial changes in some delta(15)N records in the WP could imply that the glacial decrease in subsurface delta(15)N due to less denitrification in source waters from the ETP would have been isotopically compensated by a synchronous decrease in local N(2) fixation.