State auditors estimate that Nevada taxi drivers overcharged passengers $15 million last year by taking roundabout routes to and from the airport.
A legislative audit released Monday says auditors found potential "long-hauling" in nearly 23 percent of the driver trip sheets they reviewed.
Auditors say the state Taxicab Authority is taking steps to detect long-hauling, but needs to do more to ensure tourists aren't having a negative experience while visiting Las Vegas.
The report also criticized the authority for not auditing individual cab companies for more than 3 1/2 years.
Officials say the Legislature allocated more money for audits in 2003, but managers at the authority are assigning staff members to other tasks.
Taxicab Authority officials weren't immediately available for comment on Monday morning.