Silicon microstrip detectors with 50 mu m readout pitch were connected to fast LHC-type analogue readout electronics (DMILL SCT32A) and their performance evaluated before and after irradiation. The p-type strips with a length of 4 cm were fabricated on high-resistivity n-bulk wafers by CSEM. Fast neutrons from the TRIGA research reactor in Ljubljana were used to irradiate detectors to two different fluences: 4.5 x 10(13) and 1.5 x 10(14)/cm(2) 1 MeV neutron equivalent non-ionizing energy loss. A Sr-90 beta source setup was used for detector performance measurements. Most of the observed signal/noise degradation after il radiation could be attributed to the signal loss. Around 82% charge collection efficiency was measured at higher fluence 100 V above full depletion voltage as determined with C-V measurements. Measurements were performed during annealing and reverse annealing of effective dopant concentration. (C) 2000 Elsevier Science B.V. All rights reserved.