The National Party received more than $195,000 in anonymous donations in the 2011 election campaign, according to official records.
Details of political parties' expenses and donations in the campaign were released by the Electoral Commission on Wednesday.
National, which went on to win November's election, had the biggest budget, spending $2.321 million on advertising.
The cost included $90,000 for its campaign theme song and $26,000 on an automated phone message from leader John Key to 250,000 households in the last two weeks of the campaign.
The party also received more than $195,000 worth of anonymous donations. Five donors, whose details are known only to the Electoral Commission, gave National $192,415. It also received $3000 in anonymous donations of under $1500.
The ACT Party received $61,730 in disclosed donations that went through the commission, as well as $8042 in anonymous donations of less than $1500.
The fledgling Conservative Party was the second-biggest spender behind National.
The party did not make it into Parliament and spent $1.878 million on advertising - nearly $100,000 more than the main opposition Labour Party.
Labour spent $1.789 million, including nearly a $100,000 on online advertising, and received $5500 in small anonymous donations.
New Zealand First received $27,000 in small anonymous donations.