The Rotorua Marathon is expected to bring up to $11 million into the local economy with an estimated 30,000 visitors heading to town.
Organisers say the 50th anniversary of the race on May 3 will be the biggest in the event's history and the largest marathon field in New Zealand.
Entries have already topped the 7000 mark with 4000 people taking on the iconic 42.2km marathon. There is also a half-marathon, quarter-marathon and 5km event.
Organisers Event Promotions expect to break 10,000 by race day as hundreds of entries are made each day.
The entry numbers eclipse those for the Auckland and Wellington marathons. The previous largest Rotorua Marathon was the 25th in 1989 when 6300 runners entered.