The first-time use of both active and passive microwave instruments onboard Tropical Rainfall Measuring Mission (TRMM, launched in late 1997) has made TRMM the foremost satellite for the study of precipitation in the tropics. One of the key goals of TRMM has been to define the spatial and seasonal climatological rainfall in the tropics as accurately as possible in order to quantify this key component of the hydrological cycle. A new climatology of tropical surface rain will be described based on a composite of thirteen years (1998-2010) of precipitation products (Version 6) from TRMM. The TRMM Composite Climatology (TCC) consists of a merger of selected TRMM rainfall products over both land and ocean to give a "TRMM-best” climatological estimate. Inputs to the composite were selected based on knowledge of the performance of the retrievals, limitations of the algorithms, and the presence of artifacts. In addition to the mean precipitation estimates, the TCC includes the variation among the three estimates at each point to give an estimate of the error in the estimated mean value. For the evaluation and validation purpose, the TCC estimates are compared with other satellite-based and ground-based rainfall estimates including Global Precipitation Climatology Centre (GPCC) and NOAA Climate Prediction Center (CPC) raingauge datasets over southeastern US, as well as Pacific Rainfall Data Base (PACRAIN) atoll raingauge dataset over western and central Pacific. This new climatology is very encouraging and may have broad applications. The TCC should be useful to the user community interested in climate monitoring, climate variability studies, model initialization and verification, and comparison with other non-TRMM rainfall analysis.