Twelve conformers of non-ionized β-alanine have been investigated using high level ab-initio methods. Geometry optimizations and frequency calculations have been performed at MP2/6-311G(d,p) and MP2/6-311++G(d,p) levels of calculation. Relative energies, rotational constants, harmonic vibrational frequencies and infrared intensities are reported. The relevance of using basis sets including diffuse functions has been supported. A factor of 0.9814 is proposed to scale the MP2/6-311++G(d,p) vibrational frequencies. The good agreement between the theoretical results and the available experimental values supports the reliability of the MP2/6-311++G(d,p) level of theory for describing the conformational behavior of molecules with internal hydrogen bonds.