Crystallization of p-acetanisidide (PAC) was carried out in the presence of p-acetoacetanisidide (APAC) as a solute analogue impurity. Addition of APAC into the supersaturated solution of PAC did not affect the structure of crystals of PAC, but affected the nucleation and crystal growth and also the morphology (crystal shape) of PAC crystals. APAC made the induction period before the beginning of precipitation of PAC crystals longer. The growth rate of PAC crystals was decreased. In particular, the growth of 11001 surface was inhibited, resulting in the change of the crystal shape from plate-like to rod-like. Hydrogen bonding between PAC and APAC in solution was observed by analyzing the chemical shift of N-H hydrogen. As a result, the effects of APAC on the crystallization of PAC could be explained in terms of the hydrogen bonding between PAC and APAC molecules.