The present invention is an injection port assembly for subcutaneous delivery of medication. A single molded body has a soft cannula extending downward from a generally flat bottom surface and a self-sealing septum mounted at the center of a top surface which is generally of a concave shape sloping downward towards its outer perimeter at which point the single body is very thin. The single body also has a tubular extension which is directed outward parallel to the skin's surface. A metal needle which penetrates through the septum and through the lumen of the soft cannula is used for inserting the cannula through the skin. Once the soft cannula is placed subcutaneously, the needle is removed and an adhesive tape is placed over the single body and onto the skin beyond the body's outer perimeter. By having a distal section of the needle which is smaller in diameter as compared to most of the needle's length, and by having the soft cannula fit tightly onto the needle, most of the cannula's length will be in tension during insertion thereby preventing an accordion-like compressional failure of the cannula. A quick-release connector on the proximal end of the tubular extension or mounted directly on the injection port assembly allows the tubing connecting the injection port assembly to a portable medication pump to be disconnected when the patient showers or performs some similar activity.