The Middlesex Championships.^[1] or Middlesex Lawn Tennis Championships^[2] and also known as the Middlesex Open Tennis Championships was a men's and women's grass court tennis founded at the Chiswick Park Lawn Tennis Club,Chiswick Park, Chiswick, Middlesex, Great Britain in 1884 and known as the Chiswick Park Club Open Lawn Tennis Tournament ^[3] during the early editions of the event. The tournament was staged annually until 1949.^[4]

In 1883 William Cavendish, 7th Duke of Devonshire decided to lease some of his land, with a low annual ground rent for the residents Chiswick who wanted to establish a sports club.^[4] This new sports ground staged bowls, cricket, football, and lawn tennis. In Chiswick Park Cricket and Lawn Tennis Club was formed and established a Middlesex County Championship tennis tournament.^[4] The championships were usually held annually at the end of July through to the third week August.^[4] In 1887 "Challenge Cups" were presented to the winners of the men's and women's singles events. In 1893 the scheduling of the tournament was altered to start at the end of May through to early June.

The Chiswick Park Lawn Tennis Club continued to stage the annual Championship of Middlesex,^[5] making the venue second only to Wimbledon in importance. In 1925 the land lease arrangement came to end due it expiring, however by this point the former tennis and cricket clubs had by this point formed into a business entity the Chiswick Cricket and Lawn Tennis Company. The tournament was not held during World War One and was postponed again in 1939 following the outbreak of World War Two. In 1946 the tournaments grounds were issued with a compulsory purchase by Brentford and Chiswick Urban District Council.^[4] After this tournament staged only three more times for the men's events, the women's events ended in 1946.^[4] The Middlesex Championships ran for 59 years, and was quite successful in attracting attract top players to four championships until 1949 when it was abolished.

Notable winners of the men's singles included Charles Walder Grinstead (1884), Ernest Wool Lewis (1886–1890, 1892),^[6] Athar-Ali Fyzee, (1921), Henry Mayes (1926) Daniel Prenn (1935), Czeslaw Spychala (1946) and Ghaus Mohammad (1947). Previous women's singles champions included Maud Shackle (1891–1893), Edith Austin Greville (1894, 1905), Molla Bjurstedt Mallory (1926) and Jadwiga Jędrzejowska (1938).