Leaside Aerodrome was an airport in the Town of Leaside, Ontario (now a neighbourhood of Toronto). It opened in 1917 as a Royal Flying Corps airfield during the First World War.
Unlike nearby Armour Heights Field, the airfield was not abandoned at the end of the war, but was acquired for use by the Toronto Flying Club. After the war, the airstrip became the site of Canada's first delivery of airmail on June 24, 1918 when pilot Brian Peck delivered 120 letters from Montreal (taking off from Bois-Franc Field). This delivery was initially organized at the behest of some of his friends in Montreal who wanted letters delivered to Toronto; however when the Post Office Department heard of the plans, they gathered together the letters as a test of an airmail system.
The Toronto Flying Club closed the airport in 1931. From June 1942 - March 1944, the Royal Canadian Air Force (RCAF) operated No. 1 RDF (Radio Direction Finding) School at Leaside, and the station was briefly known as RCAF Station Leaside. Although the airport was replaced with industrial uses, the last hangar was not removed until 1971.
The area is now primarily home to small industrial businesses.