This work describes the fabrication and evaluation of small core diameter Polymeric Optical fibres (POF) prepared from Poly(Methyl Methacrylate) (PMMA). Based on prior study, POF has a very interesting property in terms of short-reach local area networks due to the simpler manufacturing process and inherent immunity to electromagnetic interference and radiation. It can overcome the limiting factors of conventional glass-based optical fibre in terms of cost-effective, flexibility and easy installation. This study focused on introducing effective fabrication method to produce small diameter PMMA POF core using extrusion process. Prior to extrusion, we managed to produce PMMA cores with diameters of 650 μm, 750 μm and 850 μm. Based on the outcome of this study, the drawing tension and extrusion temperature have been identified as major influences on core diameter. The SEM images indicated that dense structure and clean surface whereas DSC and TGA analyses revealed that almost similar glass transition temperature and degradation weight loss in between fabricated PMMA core and industrial polymer optical fibre. © 2019 Penerbit UTM Press. All rights reserved.