Collocated measurements by the microwave radiometer (MWR) and the Along Track Scanning Radiometer (ATSR) on the ERS-2 satellite are used to develop algorithms for estimating global total water vapor content (TWV) over the global oceans from ATSR data. The three ATSR infrared bands that view the Earth's surface through two different view angles are treated as sounding channels. Agreement between the MWR and ATSR estimates of nadir TWV are within 0.3 cm of precipitable water. The TWV algorithms are applied to global ATSR data sets and to two small samples of collocated ATSR and radiosonde data over the open ocean. A comparison is made between the August 1997 monthly average TWV distributions obtained from ATSR and the global NASA Water Vapor Project data set.