Tenuta San Guido is an Italian wine producer in the DOC Bolgheri in Toscana, known as a producer of "Super Tuscan" wine. Its wine Sassicaia is considered one of Italy's leading Bordeaux-style red wines. The estate also produces a second wine, Guidalberto, and the third wine Le Difese. Sassicaia is member of the Primum Familiae Vini.

Tenuta San Guido was established by Mario Incisa della Rochetta. Considered the seminal "Super Tuscan", the name Sassicaia (Italian sasso meaning stone) indicating a stony field,originated in 1948 when first produced by Incisa della Rochetta using Cabernet Sauvignon vines reputedly sourced from Château Lafite-Rothschild, and for years only used for family consumption. From 1968, internationally renowned consultants were engaged to improve the production, such as Giacomo Tachis and Émile Peynaud. Small commercial quantities were not released until in the mid 1970s.

At a 1978 Decanter tasting of "great clarets", a panel including Hugh Johnson, Serena Sutcliffe and Clive Coates awarded the 1972 Sassicaia victory over a field of 33 wines from 11 countries, and established the wine's international reputation. Since the 1980s the position of Sassicaia has been by some accounts eclipsed by Ornellaia, produced by the property adjacent to Tenuta San Guido, suggested to be its owner Lodovico Antinori's competitive answer to his cousin Nicolò Incisa's Sassicaia and his older brother Piero Antinori's wine, Solaia.

In the late 1990s Sassicaia was granted its own DOC (Bolgheri), the only wine from a single estate in Italy to enjoy this privilege. Before that, and in similarity to other wines made outside the traditional DOC/DOCG regulations, Sassicaia was classified as an Indicazione geografica tipica (IGT). Initially it was a Vino da tavola, which is normally a category for wines of little complexity

Appellation: Bolgheri Sassicaia
Areas under Vine: 75 hectares
Average Annual Production: 15,000 cases
Grape Varieties: 85% Cabernet Sauvignon and 15% Cabernet Franc