Sh2-99 (Sharpless 99) and Sh2-100 (Sharpless 100) are two H II emission nebulae and active star-forming regions located in the plane of the Milky Way within the constellation Cygnus.

Both regions are embedded in the larger W58 complex, a massive molecular cloud complex and powerful radio source situated thousands of light-years away along the Perseus Arm of the Milky Way.