Published Thursday, 12 November 2009
The death was confirmed in the latest Department of Health weekly update.
The adult is understood to have had an underlying health condition.
A total of 11 people have now died of a swine flu-related illness in Northern Ireland.
The latest figures also show a further slowing down of the number of hospital cases and doctor consultation.
Health Minister Michael McGimpsey said: "A further decrease in consultation rates in the past week is encouraging and suggests that our preparations are working.
"However, swine flu still continues to circulate widely in the community and it is vital that we do not become complacent."
He also expressed his sympathy to the family of the latest victim.