Fading caused by precipitation, multipath transmission and other causes has been measured in experimental microwave paths operating in the 10.7–11.7Gc/s frequency band. Multipath signals have been analysed and used to compute the intermodulation distortion likely to occur on various-capacity systems. Diurnal and monthly variations of fading equal to or greater than an arbitrary level are given, together with the association between activity on paths taken in pairs. For the month of August 1964 the hourly mean noise powers have been calculated.Over the period for which observations were carried out, it is concluded that neither precipitation nor intermodulation arising from multipath transmission would have significantly restricted the use of the 10.7–11.7Gc/s band for multichannel telephony.