The analysis of the Nobeyama radio heliograms at 17 GHz with a restricted range of the brightness temperature revealed a new phenomenon of the large-scale solar activity: microwave blob chains with characteristic sizes comparable with the solar disk diameter. The blobs consisting the chains have angular sizes of 30-60 arcseconds and the brightness temperature of Tb ~ (11 - 15) ~ 103 K. Long-living chains exist over many days and may coincide with sharp boundaries of coronal holes, observed with Yohkoh/SXT. Transient microwave chains with a time scale of tens of hours appear to be associated with coronal mass ejections revealed by long-duration events in the soft X-ray and microwave range