The 1965–66 Rugby Union County Championship was the 66th edition of England's premier rugby union club competition at the time.
Middlesex won the competition for the fifth time after defeating Lancashire in the final.
Final
John Willcox (capt) Headingley Ted Rudd St Helens Chris Jennins Waterloo R Davies Broughton Park M Smythe Broughton Park Tom Brophy Liverpool W R M French Waterloo Nick Drake-Lee Manchester T Housley Wigan M J Hindle Fylde Barry Jackson Broughton Park A R Trickey Sale Dick Greenwood Waterloo R F Irving Liverpool T Kirchen Liverpool Gordon MacDonald (capt) London Scottish Sandy Hinshelwood London Scottish J Wilson Bristol T M Rutter Westminster Hospital Hamish Keith Wasps R J A Thomas London Welsh J H Montgomery London Scottish J H Kent Old Millhillians Steve Richards Richmond B M Stoneman Richmond Victor Harding Harlequins Chris Ralston Richmond J A D Wyness Saracens C W Thorburn Guy's Hospital George Sherriff Saracens
See also English rugby union system Rugby union in England
References