The results of five years of development of the inner tracking system
of the HERA- B experiment and first experience from the data
taking period of the year 2000 are reported. The system
contains 184 chambers, covering a sensitive area of about (20*
20) cm2 each. The detector is based on microstrip gas counters
(MSGCs) with diamond like coated (DLC) glass wafers and gas
electron multipliers (GEMs).