The possibility of preparing new analogs of L-arginine phosphate monohydrate, (LAP), has been investigated. Single crystals of the compound L-Arg . HCOOH, which had earlier been obtained in powdered form, were successfully grown during the course of this investigation. In addition, we have found that there is a class of compounds having the Arg . 2Ax composition, (where Ax is one of several inorganic or organic acids). Such compounds (Arg . 2HIO(3), Arg . 2HNO(3), Arg . 2H(3)PO(4), Arg . 2HF, Arg . 2HCl . H2O, and Arg . 2HBr . H2O) have been synthesized and single crystals grown. The crystals grown in this investigation were studied by IR and X-ray diffraction methods. The influence of the different amino acid groups on crystal symmetry and the influence of this symmetry on non-linear optical properties are discussed.