Fonseca owes its international reputation to its iconic 1840 vintage port. It was founded in 1815, and four families have shaped the company originally established by the Fonseca and Monteiro families. They were followed by the Guimaraens who ran the business for over a century and established its reputation as a Premier Cru vintage port house. They were succeeded by the Yeatmans, who took over the reins at Fonseca in the second half of the 20th century. In the closing decades of the 20th century, Fonseca acquired a number of domaines in the Douro valley. The three domaines owned by the company are Cruzeiro and Santo Antonio (in the Pinhao valley) and Panascal (in the Tavora Valley). They are all managed organically. Fonseca is now owned by Taylor and David Guimaraens is in charge of vinification at the ultra-famous domaines.

In years when Fonseca does not produce a traditional Vintage Port, it is entitled to produce Guimaraens Vintage Port instead. This port is made in years which produce soft wines which are more accessible in their youth – following much the same model as the second wines of Bordeaux. The wines are generally fruity but with genuine complexity, coming as they do from the same terroirs as the traditional vintage. Their keeping potential is lower than that of the traditional vintage, but it is still significant.