A scalpel is disclosed, having a conventional handle and a blade unit for releasable attachment to the handle. The blade unit includes a body, a slot within said body to releasably engage the finger protruding from the handle, a scalpel blade attached to said body, and a blade cover slideably engaged to said body and configured for movement between a forward, protective position fully covering said blade and a retracted position to expose said blade for use. The cover has open front and rear ends to permit said blade and said body respectively to protrude through opposing ends of said cover when said cover is moved between said positions.
