Effect on crystalline perfection, second harmonic generation (SHG) efficiency, laser damage threshold (LDT) and optical transparency due to Mn2+ doping in L-alanine crystals has been investigated. The crystalline perfection of pure and doped crystals was evaluated by high-resolution X-ray diffractometry, which revealed the improvement in the crystalline perfection at low and moderate doping concentrations. At moderate and high concentrations, the Mn2+ ions were found to be incorporated predominantly at the interstitial sites of the crystalline matrix. The actual incorporated amount of dopants in the crystals was analyzed by atomic absorption spectroscopy. The optical transparency. SHG efficiency, and laser damage threshold of the grown crystals with different concentrations of Mn2+ were investigated. From these studies it is revealed that Mn2+ doping lead to a considerable enhancement in the measured nonlinear optical properties with a correlation on crystalline perfection. (C) 2011 Published by Elsevier B.V.