U train may refer to:

• Unused New York City Subway service labels
• The London Underground
• Underground Railroad

• Classes in World of Warcraft
• Classes of computers
• Classes Of Food
• Classes of offenses under U.S. federal law
• Classes of Supply
• Classes of United States senators
• Classes plantarum
• Classe tous risques
• Classeya aphrodite
• Classeya argyrodonta
• Classeya bicuspidalis
• Classeya bleszynskii
• Classeya hexagona
• Classeya interstriatellus
• Classeya luteomarginata
• Classeya medea
• Classeya niveifascialis
• Classeya palcydioni
• Classeya placydioni
• Classeya preissneri
• Classeya quadricuspis
• Classeya symetrica
• Classeya trichelites
• Class-F
• Class Fa cable