3400 series may refer to:

• Keisei 3400 series, a Japanese train type operated since 1993
• PowerBook 3400c

• Lepuix
• Lepuix-Neuf
• Le Puley
• Lepuropetalon
• Lepus3
• LePUS3
• Lepus corsicanus
• Lepushe,
• Lepushe
• Lepus in Chinese astronomy
• Lepus tibetanus
• Lepus tolai
• Lepusul River
• Leputation of the Slaves
• Le puy
• Le Puy (disambiguation)
• Le Puy-en-Velay - Loudes Airport
• Le Puy Foot 43 Auvergne
• Le Puy - Loudes Airport
• Lepyoshkas
• Lepypiranga
• Lepyrodes
• Lepyrodia
• Lepyronia quadrangularis
• Lepyrotica