Hamilton international airport made a loss of $479,000 in the year to June.
This compares to a profit of $3.8 million in the previous year.
Waikato Regional Airport Ltd chair Jerry Rickman says it was an extremely difficult year for the company, with the gradual reduction and ultimate suspension by Air New Zealand of trans-Tasman flights from Hamilton.
Revenue was $5.8 million, down from $10.5 million last year, with expenses climbing from $6.6 million to $6.8 million.
Mr Rickman says fewer domestic flights and lower passenger numbers also contributed to the result.
Total passenger numbers were down 19% at 341,507, but are expected to stabilise this year before growing again in the 2010-11 year.