Abstract: Based on the laminar microstructure formed by ferrite andcementite with very fine interlamellar spacing, and the morphology ofmicrodefects in the ferrite, cementite and interface, a unifieddamage evolution is proposed by making use of the work dissipated on damage.It is then embedded in the constitutive model of each phase and a damageelastoplastic constitutive model is obtained for a single pearlitic colony.The damage constitutive description for pearlitic materials is formulatedusing the Hill's self-consistent scheme by assuming that a pearliticmaterial element is an aggregate of numerous cells of pearlitic colonieswith randomly distributed orientations. It is significant that the obtainedconstitutive description contains explicitly the interlamellar spacing as amicrostructure parameter, which easily accounts for the better comprehensivemechanical properties of the pearlitic materials with smaller interlamellarspacing. The constitutive behavior of pearlitic steel is simulated, and comparedwith the experimental results.