H49 may refer to :

• HMCS Margaree (H49), a 1932 Royal Canadian Navy D class destroyer
• HMS Diana (H49), a 1932 British Royal Navy D class destroyer
• HMS H49, a 1919 British Royal Navy H class submarine
• HMS Inconstant (H49), a 1942 British Royal Navy I-class destroyer
• Nelson H-49 aircraft engine

and also :

• Paralytic strabismus ICD-10 code

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