General elections were held in Thailand in April 2006. Elections for the lower house of the Thai National Assembly, the House of Representatives, were held on 2 April 2006 and elections for the upper house, the Senate, were held on 19 April 2006. The Constitutional Court later invalidated the House of Representatives election results and ordered a new round of voting.

The ruling Thai Rak Thai (TRT) party of Prime Minister Thaksin Shinawatra won a majority seats in the House of Representatives, partly as a result of the decision by the major opposition parties to boycott the elections. Nearly complete results showed that TRT received 61% of the valid vote and about 460 of the 500 seats. Despite this, Thaksin announced his resignation two days after the election.

Although TRT easily won the election in terms of both votes and seats, the results were seen by Thaksin's opponents and media critics as a rejection of his call for an overwhelming mandate. In parts of Bangkok and in southern Thailand, most TRT candidates were elected on minority votes after the majority of voters used the "abstain" option on their ballot papers. In a number of southern seats TRT candidates failed to poll the required 20% of registered voters, rendering these southern seats invalid and resulting in party dissolution charges against Thai Rak Thai and Democrat Parties. TRT won all the seats in the Northern and North-Eastern (Isan) regions, and also in the Central region apart from Bangkok.

Due to the election result, King Bhumibol Adulyadej took the unprecedented step of calling the elections undemocratic, and the election was declared invalid by the Constitutional Court. New elections were scheduled for October 2006, but were canceled when the military overthrew the government.

The elections followed the decision by Prime Minister Thaksin to dissolve the House of Representatives. King Bhumibol Adulyadej granted Thaksin a dissolution even though the last election was held only in February 2005, and even though Thaksin's party had a huge majority in the House. At the February 2005 election, the TRT won 375 seats out of 500, with its former coalition partner, the Thai Nation Party taking 26 seats. The opposition Democratic Party of Thailand won 96 seats.

Thaksin's decision to call early elections followed a mounting campaign of criticism of his personal financial dealings. In January the government changed regulations for telecommunications companies allowing an increase in foreign ownership from 24% to 49%, and within the same month he and his family sold its stake in Shin Corporation, a leading communication company, for 73 billion baht (about $US1.88 billion), an enormous profit on which the Shinawatras legally paid no tax, even though family members bought and sold shares in the company in a 24-hour period. This sparked a series of angry demonstrations in the capital. Nevertheless, Thaksin's parliamentary position was under no threat.

The English-language newspaper the Bangkok Post reported Thaksin as saying, "I cannot allow mob rule to supersede the law," and citing intelligence reports of "instigators of violence" seeking to exploit the divisive situation as a reason for dissolving the House of Representatives. The country could not suffer a new round of "bruises" when it was still suffering from the violent events of May 1992, with relatives of victims still to be healed, Thaksin said.

Thaksin also cited the impact on the economy of the political situation, pointing to the questions it had raised about the future of megaprojects and the ups and downs on the stock market. "I am ready to accept the decisions of the people. But I will never accept those outside the system who claim to be deciding for the people," he said.