Results of attenuation measurements taken during the period June 1977–April 1978 (using Microwave Radiometers designed and fabricated at NPL at 10 and 11 GHz) are presented. The results reported here pertain to rainstorm conditions and their corresponding attenuation. Rain rate necessary for computation were obtained using a fast-response raingauge recently installed at NPL and operated simultaneously with radiometer. Average attenuations are found to be around 1 dB for rainfall rate of 10 mm/hr, 5 dB for 50 mm/hr and 10 dB for 100 mm/hr. Values of attenuation with corresponding rain rate are in agreement with those obtained with radiometers in Slough, England and elsewhere in Europe, but the probability of occurrence of attenuation over New Delhi is higher than the values observed over Slough and lies between those of Klang, Malaysia, and Slough, England. Comparison has also been made of attenuation in dB/km at 11 GHz with theoretically-calculated values and are found to be in agreement. Attenuation is found to be around 2 dB/km for 50 mm/hr rain rate whereas for 100 mm/hr, it is around 4 dB/km.