The bank says the documents were handed in to a business in Galway on the day they were lost
AIB says it has retrieved missing documents containing details of around 550 customers.
The bank earlier this week confirmed that information relating to banking facilities was mislaid in Galway on August 31st.
In letters sent to affected customers, AIB said the information included names and details of balances.
In a statement today, the bank said the documents have now been found.
A spokesperson for the bank said: "The mislaid documentation was located on the evening of the 12th September when a business owner in Galway contacted AIB to inform us the documentation was handed in to his premises on the day it was mislaid.
"All information has been retrieved. The Data Protection Commissioner has been informed. Customer contact commenced yesterday and is well advanced."