A scalpel (10) having a handle assembly (16) and one of a plurality of modular blade assemblies (18). Each blade assembly includes a casing (46) within which is a retractable rod (48) having a distal end to which is permanently affixed a blade (12), and also includes a spring (56) having an unstressed state wherein the retractable rod and its blade are retracted within the casing. The handle assembly (16) includes a handle casing (20) within which is slidably disposed a handle rod (32) that is manipulatable between a retracted position and an active position with respect to the handle casing. In the active position, the handle rod's distal end engages and pushes the proximal end (66) of the retractable rod (48) to urge the blade (12) distally for performance of a procedure, while in the retracted position, the handle rod (32) permits the retractable rod (48) to self-retract within its casing (46).