Cracking is one of the major problems faced with the Czochralski growth of lead molybdate (PbMoO4, LMO) crystals. While, the effect of growth direction and temperature gradients are known to cause cracking in LMO crystals, this study for the first time shows the dependence of cracking on crystal stoichiometry. Visual examination and optical transmission measurements carried out show that small deviations from stoichiometry toward Pb-rich compositions cause lattice strain, which is in excess of the breaking strain of the material. (c) 2006 Elsevier B.V. All rights reserved.