In the "Nun's Priest's Tale", a vain cock Chauntecleer is tricked by a fox on Syn March bigan thritty dayes and two. Readers apparently understood this line to mean "32 March", i.e. April 1.

However, it is not clear that Chaucer was referencing April 1, since the text of the "Nun's Priest's Tale" also states that the story takes place on the day when the sun is in the signe of Taurus had y-runne Twenty degrees and one, which cannot be April 1.

A disputed association between April 1 and foolishness is in Geoffrey Chaucer's The Canterbury Tales (1392).

Some writers suggest that April Fools' originated because in the Middle Ages, New Year's Day was celebrated on March 25 in most European towns, with a holiday that in some areas of France, specifically, ended on April 1, and those who celebrated New Year's Eve on January 1 made fun of those who celebrated on other dates by the invention of April Fools' Day.

In 1508, French poet Eloy d'Amerval referred to a poisson d'avril (April fool, literally "fish of April"), possibly the first reference to the celebration in France.

In 1561, Flemish poet Eduard de Dene wrote of a nobleman who sent his servants on foolish errands on April 1.

In the Netherlands, the origin of April Fools' Day is often attributed to the Dutch victory in 1572 at Brielle, where the Spanish Duke Álvarez de Toledo was defeated.

In 1686, John Aubrey referred to the celebration as "Fooles holy day", the first British reference.

On April 1, 1698, several people were tricked into going to the Tower of London to "see the Lions washed".

In the UK, an April Fool prank is sometimes later revealed by shouting "April fool!" at the recipient, who becomes the "April fool". A study in the 1950s, by folklorists Iona and Peter Opie, found that in the UK, and in countries whose traditions derived from the UK, the joking ceased at midday.

In one famous prank in 1957, the BBC broadcast a film in their Panorama current affairs series purporting to show Swiss farmers picking freshly-grown spaghetti, in what they called the Swiss Spaghetti Harvest.

In 1962, Swedish national television broadcast a 5-minute special on how one could get color TV by placing a nylon stocking in front of the TV. A rather in-depth description on the physics behind the phenomenon was included. Thousands of people tried it.

In 1969, the public broadcaster NTS in the Netherlands announced that inspectors with remote scanners would drive the streets to detect people who had not paid their radio/TV tax ("kijk en luistergeld" or "omroepbijdrage"). The only way to prevent detection was to wrap the TV/radio in aluminium foil. The next day all supermarkets were sold out of their aluminium foil, and a surge of TV/radio taxes were being paid.

Jovian–Plutonian gravitational effect: In 1976, British astronomer Sir Patrick Moore told listeners of BBC Radio 2 that unique alignment of two planets would result in an upward gravitational pull making people lighter at precisely 9:47 am that day. He invited his audience to jump in the air and experience "a strange floating sensation". Dozens of listeners phoned in to say the experiment had worked, among them a woman who reported that she and her 11 friends were "wafted from their chairs and orbited gently around the room."

Great Blue Hill eruption prank: On April 1, 1980, Boston television station WNAC-TV aired a fake news bulletin at the end of the 6 o'clock news which reported that Great Blue Hill in Milton, Massachusetts was erupting. The prank resulted in panic in Milton, where some residents began to flee their homes. The executive producer of the 6 o'clock news, Homer Cilley, was fired by the station for "his failure to exercise good news judgment" and for violating the Federal Communications Commission's rules about showing stock footage without identifying it as such.

In 1993, a radio station in San Diego, California told listeners that the US Space Shuttle had been diverted to a small, local airport. Over 1,000 people drove to the airport to see it arrive in the middle of morning rush hour. There was no shuttle flying that day.

The negative view describes April Fools' hoaxes as "creepy and manipulative", "rude" and "a little bit nasty", as well as based on schadenfreude and deceit. When genuine news or a genuine important order or warning is issued on April Fools' Day, there is risk that it will be misinterpreted as a joke and ignored. For example, when Google, known to play elaborate April Fools' Day hoaxes, announced the launch of Gmail with 1-gigabyte inboxes in 2004, an era when competing webmail services offered 4-megabytes or less, many dismissed it as a joke outright. On the other hand, sometimes stories intended as jokes are taken seriously. Either way, there can be adverse effects, such as confusion, misinformation, waste of resources (especially when the hoax concerns people in danger) and even legal or commercial consequences.