A member of the Italian Republican Party (Partito Repubblicano Italiano; PRI), he was minister of Mail and Telecommunications from 1987 to 1991.

After having been undersecretary of Industry and Trade, he was first Minister of Parliamentary Relations in the Craxi I and Craxi II Cabinets, and later Minister of Mail and Telecommunications in the Goria, De Mita and Andreotti VI Cabinets.

His name is connected with the so-called "Mammì Bill", issued in 1990, which was the first Italian comprehensive law dealing with media and TV and Radio advertisement.

The law was accused of granting a substantial monopoly on public television to Silvio Berlusconi.

The Italian Constitutional Court later in 1994 declared as anti-constitutional a comma of the law which allowed Berlusconi to own three TV networks; however, there was no measure to change the situation afterwards.