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diff --git a/rand/rand_distr/src/unit_circle.rs b/rand/rand_distr/src/unit_circle.rs
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+// Copyright 2018 Developers of the Rand project.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use rand::Rng;
+use crate::{Distribution, Uniform, uniform::SampleUniform};
+use crate::utils::Float;
+
+/// Samples uniformly from the edge of the unit circle in two dimensions.
+///
+/// Implemented via a method by von Neumann[^1].
+///
+///
+/// # Example
+///
+/// ```
+/// use rand_distr::{UnitCircle, Distribution};
+///
+/// let v: [f64; 2] = UnitCircle.sample(&mut rand::thread_rng());
+/// println!("{:?} is from the unit circle.", v)
+/// ```
+///
+/// [^1]: von Neumann, J. (1951) [*Various Techniques Used in Connection with
+///       Random Digits.*](https://mcnp.lanl.gov/pdf_files/nbs_vonneumann.pdf)
+///       NBS Appl. Math. Ser., No. 12. Washington, DC: U.S. Government Printing
+///       Office, pp. 36-38.
+#[derive(Clone, Copy, Debug)]
+pub struct UnitCircle;
+
+impl<N: Float + SampleUniform> Distribution<[N; 2]> for UnitCircle {
+    #[inline]
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> [N; 2] {
+        let uniform = Uniform::new(N::from(-1.), N::from(1.));
+        let mut x1;
+        let mut x2;
+        let mut sum;
+        loop {
+            x1 = uniform.sample(rng);
+            x2 = uniform.sample(rng);
+            sum = x1*x1 + x2*x2;
+            if sum < N::from(1.) {
+                break;
+            }
+        }
+        let diff = x1*x1 - x2*x2;
+        [diff / sum, N::from(2.)*x1*x2 / sum]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Distribution;
+    use super::UnitCircle;
+
+    /// Assert that two numbers are almost equal to each other.
+    ///
+    /// On panic, this macro will print the values of the expressions with their
+    /// debug representations.
+    macro_rules! assert_almost_eq {
+        ($a:expr, $b:expr, $prec:expr) => (
+            let diff = ($a - $b).abs();
+            if diff > $prec {
+                panic!(format!(
+                    "assertion failed: `abs(left - right) = {:.1e} < {:e}`, \
+                     (left: `{}`, right: `{}`)",
+                    diff, $prec, $a, $b));
+            }
+        );
+    }
+
+    #[test]
+    fn norm() {
+        let mut rng = crate::test::rng(1);
+        for _ in 0..1000 {
+            let x: [f64; 2] = UnitCircle.sample(&mut rng);
+            assert_almost_eq!(x[0]*x[0] + x[1]*x[1], 1., 1e-15);
+        }
+    }
+
+    #[test]
+    fn value_stability() {
+        let mut rng = crate::test::rng(2);
+        let expected = [
+                [-0.9965658683520504, -0.08280380447614634],
+                [-0.9790853270389644, -0.20345004884984505],
+                [-0.8449189758898707, 0.5348943112253227],
+            ];
+        let samples: [[f64; 2]; 3] = [
+                UnitCircle.sample(&mut rng),
+                UnitCircle.sample(&mut rng),
+                UnitCircle.sample(&mut rng),
+            ];
+        assert_eq!(samples, expected);
+    }
+}