Alfonso IV may refer to:

• Alfonso IV of Leon (924–931)
• Afonso IV of Portugal (1291–1357)
• Alfonso IV of Aragon (1327–1336)
• Alfonso IV d'Este (1634–1662), Duke of Modena and Regg

• E^ipi
• E Ipo
• Eipo
• Eipomek
• Eipper Aircraft
• Eipper Formance
• EIPR (disambiguation)
• Eipri
• E-IPS
• EIQ
• Eiq
• EIQ Energy
• Eira (genus)
• Eira Hospital
• Eira River
• Eira Stenberg
• Eircom Group plc
• Eircom.net
• Eircom Park
• EIR (disambiguation)
• Eir (disambiguation)
• EIRE
• Eire Canal
• Eire (Confirmation of Agreements) Act 1938
• Eireil