BBC, February 21, 2009 - The convoy of 99 vehicles, which left from the UK loaded with medicine, food, clothes and toys, crossed into Algeria near the Moroccan town of Oujda.
The frontier was shut in 1994 after Morocco accused Algeria of involvement in an attack on a hotel in Marrakech.
The convoy is due to cross from Egypt to Gaza in early March.
It left London last week, led by British member of parliament George Galloway. Its 5,000-mile route also includes France, Spain, Tunisia, and Libya.
The Gaza Strip is facing a humanitarian crisis following Israel's recent three-week offensive.
Though the Morocco-Algeria crossing was opened for the convoy, there is little sign ordinary people will be able to travel overland between Morocco and Algeria any time soon, the BBC's James Copnall reports from the Moroccan capital, Rabat.
Diplomatic relations between the two countries have long been poor, and disagreements are currently focused on the disputed territory of the Western Sahara.
Morocco considers the region its own, while Algeria supports the Polisario Front independence movement.
The border closure also has economic consequences, our correspondent says.
According to some estimates, the Maghreb has the lowest rate of internal trade of any region in the world.Morocco recently asked for the border to be reopened, but Algeria has yet to agree.
PressTV (Iran) was there and filmed this live coverage:
Follow the convoy from now until its anticipated arrival at the Rafah crossing on March 2 on the Viva Palestina web site.