Process for manufacturing hollow elongated bodies, optionally tapered poles, made of reinforced synthetic resin, comprising - for each hollow body manufacturing cycle - the following steps: - arranging, inside an elongated mould, reinforcing fibres in order to substantially cover a predominant portion of the internal surface of the mould, said internal surface of the elongated mould having a tapered shape, optionally a frusto-conical one, - introducing into said mould an amount of liquid synthetic resin comprising at least one active agent at a first concentration, the active agent being selected among: o a cross-linking catalyst, o a cross-linking accelerator, o a cross-linking agent, o an agent including one or more of one catalyst, a cross-linking accelerator, a cross-linking agent, - putting in rotation the mould around a prevalent development longitudinal axis of the mould itself in order to impregnate said reinforcing fibres with said liquid synthetic resin, - solidifying said liquid synthetic resin for forming an elongated hollow body, - extracting said elongated hollow body at the solid state from the mould, wherein: - the liquid synthetic resin introduced in said mould, during each cycle of manufacturing a respective elongated body, exhibits a mass greater than the liquid mass necessary for forming said elongated body for therefore defining a surplus mass of liquid resin, - the surplus mass is collected outside said mould, and - to the surplus mass collected outside the mould it is added a new liquid resin mass in which said active agent is present at a second concentration smaller than the one of said first concentration for forming a mixture of liquid resin. - arranging, inside an elongated mould, reinforcing fibres in order to substantially cover a predominant portion of the internal surface of the mould, said internal surface of the elongated mould having a tapered shape, optionally a frusto-conical one, - introducing into said mould an amount of liquid synthetic resin comprising at least one active agent at a first concentration, the active agent being selected among: o a cross-linking catalyst, o a cross-linking accelerator, o a cross-linking agent, o an agent including one or more of one catalyst, a cross-linking accelerator, a cross-linking agent, o a cross-linking catalyst, o a cross-linking accelerator, o a cross-linking agent, o an agent including one or more of one catalyst, a cross-linking accelerator, a cross-linking agent, - putting in rotation the mould around a prevalent development longitudinal axis of the mould itself in order to impregnate said reinforcing fibres with said liquid synthetic resin, - solidifying said liquid synthetic resin for forming an elongated hollow body, - extracting said elongated hollow body at the solid state from the mould, - the liquid synthetic resin introduced in said mould, during each cycle of manufacturing a respective elongated body, exhibits a mass greater than the liquid mass necessary for forming said elongated body for therefore defining a surplus mass of liquid resin, - the surplus mass is collected outside said mould, and - to the surplus mass collected outside the mould it is added a new liquid resin mass in which said active agent is present at a second concentration smaller than the one of said first concentration for forming a mixture of liquid resin.