The Department of Corrections has apologised to a Spring Hill prison inmate's family for failing to properly care for him before he died.

The middle aged man was twice taken to hospital with various conditions - and on both occasions instructions for further medical care in prison were not followed.

He was eventually taken back to hospital where scans showed he had cancer - and he later died in hospice care.

In a second case revealed today, Corrections has been criticised for its care of a 30-year-old Auckland Prison inmate who had a tooth extracted and was left in pain for days afterward

Corrections has acknowledged failings in both cases and says it has since made changes to see they don't happen again.