Alternating morphology transitions between dendrite and dense-branching morphology have been studied for the first time in electrochemical deposition of FeSO 4 aqueous solution film. We suggest that the observed alternating transition is caused by the interchange of anisotropy in interfacial growth, which arises from the periodic accumulation and depletion of impurities in front of the growing interface in our experimental system. The selection problem in pattern formation is discussed