The following is a list of all team-to-team transactions that have occurred in the National Hockey League during the 1977–78 NHL season. It lists what team each player has been traded to, signed by, or claimed by, and for which player(s) or draft pick(s), if applicable.
Trades between teams
May
June
Trade completed on November 3, 1977.
August
Trade completed on June 15, 1978, at the 1978 Amateur Draft.
September
October
Washington's first-round pick went to Minnesota as the result of a trade on October 18, 1978, that sent Dennis Maruk to Washington in exchange for this pick.
November
Trade completed on May 27, 1978. Trade completed on December 15, 1977.
December
January
Draft pick not exercised by Cleveland due to Barons-North Stars merger on June 14, one day prior to the 1978 NHL Amateur Draft. Draft pick forfeited by the Islanders due to Barons-North Stars merger on June 14, one day prior to the 1978 NHL Amateur Draft.
February
March
Trade completed on May 4, 1978.
Additional sources
hockeydb.com - search for player and select "show trades"