The relationship between weekly variation (3 to 10 days) of upper tropospheric humidity (UTH) and mesoscale convective systems is investigated using Megha-Tropiques observations. Launched on 12 October 2011, The satellite Megha-Tropiques has a low inclination (20°) that provides 2 to 5 samplings of the tropical atmosphere per day, thanks to two microwave radiometers (SAPHIR & MADRAS), an optical radiometer (SCARAB) and a GPS (ROSA). Although MADRAS has been recently switched off, the 14 months of high quality data of simultaneous observations with SAPHIR are explored to investigate how mesoscale convective systems impact the atmospheric humidity and the rain field. For this purpose, three different level of UTH data from SAPHIR and rain rates data estimated from MADRAS are monitored during mesoscale convective systems transit within several areas (10°x10° fixed boxes) that have been selected over both land and ocean in the tropical belt. Indeed, the mesoscale convective systems during the CINDY- DYNAMO experiment, the Indian and African monsoon and several cyclones over Atlantic, Pacific and Indian Oceans have been studied. These several case study are documented and compared with respect to location within the tropical belt, mesoscale convective system type and life cycle, rain type and intensity, asymmetry of humidity field, etc...