A safety IV catheter assembly comprising: a catheter tube having a distal end and a proximal end; a catheter hub having a distal end and a proximal end; a needle with a needle shaft extending through the catheter hub and the catheter tube having opposite proximal and distal ends defining an axial direction, wherein the proximal end is joined to a needle hub and the distal end forms a needle tip and a change in profile is provided between the proximal and distal ends of the needle; a tip protector assembly being arranged movably on the needle in-between the catheter hub and needle hub including: a base portion having a needle passage extending in the axial direction from the proximal end of the base portion to a distal side of the base portion; a hollow enclosure formed by the extension of the base portion in a direction generally parallel to the axial direction; wherein the distal end of the hollow enclosure has a substantially circular opening allowing the needle to pass there-through; first and second arms made integrally within the hollow enclosure and extending from the distal side of the base portion in an axial direction, wherein the region between the first and second arms and the hollow enclosure defines open space; at least one tension creating element surrounding partially or completely the first and second arms in a region proximal to the distal ends thereof; at least one stopper element arranged in the base portion having an axial bore with a dimension adapted to the principal outer profile of the said needle; and one or more first locking means to lockingly arrange the tip protector assembly outside the catheter hub in an arrangement engaging with one or more second locking means provided on the catheter hub in its ready position, wherein the first arm is deflected radially outwards by the needle against a restoring force of the tension creating element, characterized in that a groove is provided in the inner wall of at least one of the first and second arms extending substantially in the axial direction from the base portion, and being capable of acting as a guide groove for the needle shaft and aiding the axial movement of the needle shaft relative to the tip protector assembly. a catheter tube having a distal end and a proximal end; a catheter hub having a distal end and a proximal end; a needle with a needle shaft extending through the catheter hub and the catheter tube having opposite proximal and distal ends defining an axial direction, wherein the proximal end is joined to a needle hub and the distal end forms a needle tip and a change in profile is provided between the proximal and distal ends of the needle; a tip protector assembly being arranged movably on the needle in-between the catheter hub and needle hub including: a base portion having a needle passage extending in the axial direction from the proximal end of the base portion to a distal side of the base portion; a hollow enclosure formed by the extension of the base portion in a direction generally parallel to the axial direction; wherein the distal end of the hollow enclosure has a substantially circular opening allowing the needle to pass there-through; first and second arms made integrally within the hollow enclosure and extending from the distal side of the base portion in an axial direction, wherein the region between the first and second arms and the hollow enclosure defines open space; at least one tension creating element surrounding partially or completely the first and second arms in a region proximal to the distal ends thereof; at least one stopper element arranged in the base portion having an axial bore with a dimension adapted to the principal outer profile of the said needle; and a base portion having a needle passage extending in the axial direction from the proximal end of the base portion to a distal side of the base portion; a hollow enclosure formed by the extension of the base portion in a direction generally parallel to the axial direction; wherein the distal end of the hollow enclosure has a substantially circular opening allowing the needle to pass there-through; first and second arms made integrally within the hollow enclosure and extending from the distal side of the base portion in an axial direction, wherein the region between the first and second arms and the hollow enclosure defines open space; at least one tension creating element surrounding partially or completely the first and second arms in a region proximal to the distal ends thereof; at least one stopper element arranged in the base portion having an axial bore with a dimension adapted to the principal outer profile of the said needle; and