Nanoclay and carbon nanotubes (CNT) have been in focus recently as means of enhancing beta phase crystals formation in poly(vinylidene fluoride)(PVDF). Dominantly, the so-far work has been carried out on films/ thin sheets filled with nanoclay. It has been found, mainly from combined XRD and DSC data, that nanoclay influences the PVDF structure, and particularly the beta phase crystals formation is enhanced. Results published by various groups are in fairly good agreement. There are no results for nanoclay filled melt-spun PVDF fibres. The influence of CNT on PVDF structure has been less studied. XRD data indicating an enhancing role of multi-wall carbon nanotubes (MWNT) on beta phase crystals formation in solution compounded PVDF films are available. Published results for MWNT/PVDF films are not in good agreement. The only study into single-wall carbon nanotube (SWNT)/PVDF has been made on electrospun nanofibres. We explore above findings towards melt-spun nanofilled PVDF fibres. We present new results obtained by us for melt-spun PVDF fibres containing non-functionalized and amino-functionalized double-wall carbon nanotubes (DWNT). The key finding is that amino-DWNT can influence the beta to alpha polymorphic balance.