St Peter’s Hill Surgery in Grantham is only able to see emergency patients today (Monday, August 21).
Practice manager Catherine Dickinson said because they have no phones or electricity for computers, they were unable to access patients records.
She added: “We are unable to see anything other than absolute emergencies as we cannot safely prescribe or check records.”
The surgery apologised for any inconvenience.
The postcode is affecting NG31, NG32 and NG33 areas. Western Power Distribution expects to have the problem resolved by 2pm.