5-year-old David Lundy was last seen around 6:30 Friday night at a home on the 400 block of Meadow Road in West Windsor Township.
Investigators tell Action News that the child's grandfather - Morris "Tommy" Lundy took the boy.
David is described as a light-skinned African American boy, approximately 3'4" and weighing 55 pounds with short and sandy hair. He was last seen wearing a white and green shirt and blue cargo shorts.
Authorities are also concerned for the child's safety due to a pre-existing medical condition which requires medication.
The grandfather lives in New York and police believe that is where he is going.
Anyone with information is asked to contact West Windsor Police at 609-799-1222.