Sydenham, named after Lord Sydenham, is a community in Frontenac County, located in the municipality of South Frontenac. It is situated at the west end of Sydenham Lake and located north of Kingston, Ontario, Canada. The former Canadian Northern Railway runs through the north end of town, which when the local section was completed, formed the first rail link between Toronto and Ottawa. The abandoned railway right of way is now part of the Trans Canada Trail.