Three rest homes have been criticised by the Health & Disability Commission after elderly patients developed flesh eating infections.
Deputy Health & Disability Commissioner Rae Lamb found that the three patients did not receive adequate care. Two later died.
In one case, a woman, 92, died as a result of developing necrotising fasciitis, a bacterial infection beaneath the skin.
Ms Lamb said she should have been treated promptly, but staff at the rest home failed to act and follow policy over many months.
She also found that two other rest homes provided insufficient care for an woman, 89, who developed an infected bed sore and a man, 85, who died.
He was admitted to the rest home with a hip fracture and later developed hip ulcers which were not properly treated.
The reports do not identify the rest homes and the Green Party says the public has a right to know which ones are not providing satisfactory care.
But an organisation representing rest home owners says criticisms made by the Commission do not point to systemic problems within the sector.
Healthcare Providers New Zealand's chief executive Martin Taylor says the reports need to be kept in perspective as the industry largely provides a high level of care.
He says the sector needs to be more vigilant in making sure staff carry out the care they are trained to provide.
However, he says it is impossible to prevent mistakes from being made within such a large industry.