The atmospheric mass transfer between the Northern Hemisphere (NH) and the Southern Hemisphere (SH) across the equator is calculated from the ERA-40, the NCEP/NCAR (NCEP 1), the NCEP-DOE AMIP-2 (NCEP 2) and the Japanese 25-year Reanalysis (JRA-25) and explored for trends which have some notable differences, even contrary phase in the mean annual cycle. The hemispheric and global mean surface pressure anomalies have the coincident trends for the four datasets. The varieties of mass flux and mean surface pressure anomalies are comparatively coincident in ERA-40 and JRA-25 (when the mass flux is northerly (southerly), the mean surface pressure in NH increases (decreases)), but almost contrary verdict in NCEP 1. There's been a notable improvement in NCEP 2 upon NCEP 1, however, NCEP 2 seems likely still not as good as ERA-40 and JRA-25. Furthermore, the research also expands to 60°S–60°N.