Police say 34-year-old Brad Butler, who lives in the 4000 block of Society Drive in Claymont, Delaware, has not been seen since approximately 2:00 a.m. Saturday.
His last known possible location was in the Drexel Hill area of Pennsylvania.
New Castle officers requested assistance from the Pennsylvania State Police but they too were unsuccessful in their efforts in locating Butler.
Butler is described as a white male, 6'3 tall and 280 pounds, with blue eyes and brown hair.
Police say his medical status is such that there is a real concern for his welfare.
He was last seen operating a 7 series black BMW, possibly with a PA temporary registration plate.
Anyone with information regarding his whereabouts is asked to please contact the New Castle County Police Department at 302-573-2800.