In this paper we describe the nucleation and growth of calcium carbonate (CaCO3) in a reverse macroemulsion system based on N-stearoyl acid surfactant with head group of serine. The CaCO3 nanocrystals crystallized in the macroemulsions were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FT-IR) and X-ray diffraction. Our results indicated that crystallization of CaCO3 in macroemulsions leads to the formation of vaterite and calcite nanocrystals with a uniform size of rod-like morphology and also to the formation of amorphous CaCO3. Based on our results we propose a growth mechanism in which the stabilization of the rod-like vaterite nanocrystals is via interactions with the serine head group of surfactant. Our study demonstrates the potential application of macroemulsions to control crystals morphology and polymorphism. (C) 2008 Elsevier B.V. All rights reserved.