Iron Mine Branch is a long second-order tributary to Marshyhope Creek in Sussex County, Delaware.
Iron Mine Branch rises on the Bridgeville Branch divide at Dublin Hill, Delaware, and then flows generally northwest to join Marshyhope Creek about 1.5 miles south-southwest of Woodenhawk, Delaware.
Iron Mine Branch drains of area, receives about 44.8 in/year of precipitation, and is about 3.04% forested.