The Letter of 59 (also known as the Memorial or Memorandum of 59) was an open letter signed by 66 (or 59 at first, hence the name) Polish intellectuals who protested against the changes of the Constitution of the People's Republic of Poland that were made by the communist party of Poland in 1975.^[1] Additional people signed the letter in January 1976.

The letter was closely related to the Helsinki Accords. On September 1, 1975 the Polish socialist government signed "The Blue Book" of the OSCE (the Organization for Security and Co-operation in Europe) committing to, among other things, respect for human rights and refraining from the threat or use of force. Meanwhile, the new changes to the Polish constitution proposed by the Polish United Workers' Party after the Helsinki Accords, included new ideological clauses pronouncing and reaffirming the "steering role of the Party in the nation," the "socialist character of the nation," a "permanent and unbreakable alliance with the Soviet Union," and most of all, that the "government obligation to respect the rights of the citizens" is conditional only, and "dependent on the citizens fulfilling their obligations towards the country."

The communist government criticized the letter of protest publicly, with Edward Gierek calling the signatories "furious anticommunists, politically blind".^{[citation needed]} Eventually, although the constitution was changed, the above fragments were redrafted to sound more neutral:

1. the steering role of the Party "in the nation" was changed to "in the building of socialism"
2. "alliance" with the USSR was replaced with "friendship"
3. citizens' rights were not linked with their obligations

The government could not officially persecute the signatories for their letter, although various semi-official persecutions were implemented, for example, some authors had the government agencies refuse to print or distribute their books for several years thereafter.^{[2] [3] [4]}

Italics refer to the additional signatories from early 1976

In addition in January 1976, 78 emigrants and exiled Polish intellectuals also signed the letter, including: