Podkayne of Mars is a science-fiction novel by American writer Robert A. Heinlein, originally serialised in Worlds of If (November 1962, January, March 1963), and published in hardcover in 1963.

[1] The novel features a teenage girl named Podkayne "Poddy" Fries and her younger brother, Clark, who leave their home on Mars to take a trip on a spaceliner to visit Earth, accompanied by their great-uncle.

The book is a first-person narrative consisting of the diary of Podkayne Fries, a 15-year-old (Earth years) girl living on Mars with her parents and 11-year-old brother Clark.

Due to the unscheduled "uncorking" (birth) of their three test-tube babies, Podkayne's parents cancel a much-anticipated trip to Earth.

Disappointed, Podkayne confesses her misery to her uncle, Senator Tom Fries, an elder statesman of the Mars government.

Clark's ploy is taken from a real-life incident, related in Heinlein's Tramp Royale, in which his wife answers the same question with "heroin" substituted for the fictitious, but equally illegal, happy dust.

When Clark vanishes and even the corporation is unable to find him, Tom reveals that he is on a secret diplomatic mission, as the accredited representative of the Martian government to a vital conference on Luna (the Moon).

In a letter to Lurton Blassingame, his literary agent, Heinlein complained that it would be like "revising Romeo and Juliet to let the young lovers live happily ever after."

In the original ending, after they escape from the kidnappers to a safe distance, Podkayne remembers that a semi-intelligent Venerian "fairy" baby has been left behind, and returns to rescue it.

The story ends with a hint of hope for him, as he admits his responsibility for what happened to Podkayne—that he "fubbed it, mighty dry"—then shows some human feeling by regretting his inability to cry and describes his plan to raise the fairy himself.