We report in this work on the spectral purity of pyramidal site-controlled InGaAs/AlGaAs Quantum Dots grown by metal-organic vapour phase epitaxy on (1 1 1)B oriented GaAs substrates. Extremely sharp emission peaks were found, showing linewidths surprisingly narrow (similar to 27 mu eV) and comparable to those that can be obtained by Molecular Beam Epitaxy in an ultra-high vacuum environment. A careful reactor handling is regarded as a crucial step toward the fabrication of high optical quality systems. (C) 2010 Elsevier B.V. All rights reserved.