Labour inspectors in Queenstown say 15 employers in the South Island resort town have been found to be in breach of workers' rights.
The offences included not paying the legal minimum wage, and workers not getting public or annual holiday entitlements.
The Ministry of Business, Innovation and Employment said a total of 64 breaches were found, and seven of the businesses are being investigated further.
An official said the level of non-compliance was disappointing.
An international report recently found some people in New Zealand work in conditions akin to slavery.
In a case in Christchurch, two brothers worked in a Vietnamese restaurant for almost five years without pay.