Christchurch's tourism authority says the February earthquake has halved some operators' business.
New Zealand's second biggest city was severely damaged in the quake on 22 February.
About 75% of the city's hotel rooms are still unavailable, although most motels are open.
Christchurch and Canterbury Tourism chief executive Tim Hunter says international visitor arrivals for March were down about 30%, but that is not the whole story.
He says many new arrivals are departing the city straight away having been told the city is damaged and, as a result, many businesses are down by well over 50%.
Mr Hunter says the message needs to get out that the city is open for business.
He believes it may take a year before backpackers come back and up to three years for conventions to return to the city.