The Prime Minister says the likelihood of passing a lucrative free trade deal with the Gulf Cooperation Council is better than it was before his whistle-stop trade tour.
However, he can't say exactly what the chances of sealing the stalled agreeement are.
Mr Key first visited United Arab Emirates and later became the first New Zealand prime minister to go to Saudi Arabia and Kuwait.
Saudi Arabia, which Mr Key said was the powerhouse of the Council, has always been the stumbling block in passing the all-but-completed deal, and it appears that is still the case.
"There was always going to be a bit of a risk in coming... and bluntly we got a great reception in Kuwait, we had a fantastic reception in Dubai, the Saudis we're going to have to continue to work on that but I think we can get there," Mr Key said.
A sticking point for Saudi Arabia was the treatment of an investor in New Zealand who was caught out when live animal exports were halted.
Mr Key said the trade deal was complicated and had a number of issues.
The Gulf Cooperation Council comprises Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates and two-way trade totals $4.8 billion.
Opposition parties and Amnesty International have scrutinised how much the Prime Minister would raise - and ended up raising - Saudi Arabia's human rights record.
Amnesty International said there had been an inadequate response to what it said was Saudi Arabia's "abysmal" human rights record.
"While Mr Key has said he has raised human rights generally behind closed doors with the Saudi King, he is still repeating the Saudi line about cultural differences being behind their human rights violations," its executive director Grant Bayldon said.
Amnesty International wanted assurances that the Government would publicly raise human rights concerns in future discussions with Saudi Arabia.
Opposition MPs said Mr Key had a duty to raise concerns about Saudi Arabia's human rights abuses ahead of any trade deal.
Mr Key said his time in the Gulf states was a much better use of his time "than sitting in Wellington for days where we would have no chance of getting it over the line".
The Prime Minister had an 18-member business delegation with him, and those spoken to by Radio New Zealand were reluctant to speak about human and women's rights.
Last day in Kuwait
Mr Key was only in Kuwait for a day and met with its Emir, His Highness Sabah Al Ahmad Al Jaber Al Sabah, and Prime Minister Jaber Al Mubarak Al Hamad Al Sabah.
He also visited an outlet of New Zealand company Burger Fuel in Kuwait City.
Mr Key said New Zealand had a deepening relationship with Kuwait and that it had just established an embassy.
"We do have some trade with them but it's pretty minimal, we buy a lot of oil off them and sell a little bit of food to them but there is a fair but of potential over time," Mr Key said.
"In the end, we need all of the Gulf state council members to vote for us, and everyone we've seen from Dubai, Abudhabi, Kuwait and Saudi Arabia are those members."