Just one retailer was netted in three tobacco controlled purchase operations in Hawke's Bay in the past two months.
The single illegal sale was made by a staff member at Z Energy in Wairoa, where the employee was later issued with a $500 infringement fee.
The Hawke's Bay District Health Board said Z Energy proved it had an adequate staff training programme, and that the employee had gone through the training, so no fine was issued.
The board's director of population health, Caroline McElnay, said with 63 premises visited, overall compliance was at a high level - 16 retailers in Central Hawke's Bay and Flaxmere were approached in November, and a further 30 in Napier and Hastings in December, which were "without blemish".
"While a Z Energy staff member failed to not sell tobacco to minors during the Wairoa visits this month, a further 16 retailers did not," Dr McElnay said. "We have been told the owners of the Z Station are concerned about the breach and have since been proactive in ensuring all the station's staff are aware of the law. We applaud that attitude.