The present Letter introduces a novel approach to test the efficiency of spin crossover materials with regard to structural fatigability. By measuring single-crystal mosaicity, structural fatigability is evidenced in a gradual SCO iron compound. The non fatigability of the analogue non-SCO zinc compound demonstrates the role of SCO in such observation. The mosaicity strongly increases during the first cycles. It is therefore clearly shown that fatigability can affect non-cooperative SCO systems. Magnetic properties appear however not altered by the observed structural fatigability which is thus related to mechanical aspects of SCO. (C) 2012 Elsevier B. V. All rights reserved.