R38 is a class of British airships, of which only one was completed.

R38 may also refer to:

• R-38 (missile), a Soviet prototype air-to-air missile
• R38 (New York City Subway car)
• R38 (South Africa), a road
• HMS R38, a submarine of the Royal Navy
• HMS Victorious (R38), an aircraft carrier of the Royal Navy
• R38: Irritating to skin, a risk phrase
• Renard R.38, a Belgian aircraft
• Small nucleolar RNA R38
• Tachikawa R-38, a Japanese training aircraft
• R38, a car design of London Underground R Stock trains