The CM SAF Fundamental Climate Data Record (FCDR) of SSM/I and SSMIS brightness temperatures covers the time period from July 1987 to December 2013 including all available data from the six SSM/I radiometers aboard F08, F10, F11, F13, F14, and F15 and from the three SSMIS radiometers aboard F16, F17, and F18. It provides homogenised and inter-calibrated brightness temperatures in a user friendly data format. SSM/I and SSMIS data are used for a variety of applications, such as analyses of the hydrological cycle and related atmospheric and surface parameters, as well as remote sensing of sea ice. The improved homogenization and inter-calibration procedure ensures the long term stability of the FCDR for climate related applications. All available raw data records have been reprocessed to a common standard, starting with the calibration of the raw Earth counts, to ensure a completely homogenized data record. The data processing accounts for several known issues with the SSM/I and SSMIS instruments and corrects calibration anomalies due to along-scan inhomogeneity, moonlight intrusions, sunlight intrusions, and emissive reflector. Furthermore, the inter-calibration model incorporates a scene dependent inter satellite bias correction and a non-linearity correction to the instrument calibration. The data files contain all available original sensor data and metadata to provide a completely traceable climate data record. Inter-calibration and Earth incidence angle normalization offsets are available as additional layers within the data files in order to keep this information transparent to the users. The data record is complemented with radiometer sensitivities, quality flags, surface types, and Earth incidence angles. This is a Fundamental Climate Data Record (FCDR). An updated version of this data record is available. Users are recommended to use edition 3 of this FCDR (EO:EUM:CM:DMSP:FCDR_MWI_V003).