1diff --git a/src/RawFormulas/Math.ts b/src/RawFormulas/Math.ts
  2index 1933bb9..466d7ba 100644
  3--- a/src/RawFormulas/Math.ts
  4+++ b/src/RawFormulas/Math.ts
  5@@ -1819,6 +1819,31 @@ var EFFECT = function (...values) : number {
  6 };
  7 
  8 
  9+/**
 10+ * Returns the value of the exponential distribution function with a specified lambda at a specified value.
 11+ * @param values[0] x - The input to the exponential distribution function. If cumulative is TRUE then EXPONDIST returns
 12+ * the cumulative probability of all values up to x.
 13+ * @param values[1] lambda - The lambda to specify the exponential distribution function.
 14+ * @param values[2] cumulative - Whether to use the exponential cumulative distribution.
 15+ * @returns {number} value of the exponential distribution function.
 16+ * @constructor
 17+ */
 18+var EXPONDIST = function (...values) : number {
 19+  function cdf(x, rate) {
 20+    return x < 0 ? 0 : 1 - Math.exp(-rate * x);
 21+  }
 22+  function pdf(x, rate) {
 23+    return x < 0 ? 0 : rate * Math.exp(-rate * x);
 24+  }
 25+  ArgsChecker.checkLength(values, 3);
 26+  var x = TypeCaster.firstValueAsNumber(values[0]);
 27+  var lambda = TypeCaster.firstValueAsNumber(values[1]);
 28+  var cumulative = TypeCaster.firstValueAsBoolean(values[2]);
 29+  return (cumulative) ? cdf(x, lambda) : pdf(x, lambda);
 30+};
 31+
 32+
 33+
 34 export {
 35   ABS,
 36   ACOS,
 37@@ -1845,6 +1870,7 @@ export {
 38   EVEN,
 39   ERF,
 40   ERFC,
 41+  EXPONDIST,
 42   FDIST$LEFTTAILED,
 43   FINV,
 44   FISHER,
 45diff --git a/src/RawFormulas/RawFormulas.ts b/src/RawFormulas/RawFormulas.ts
 46index dd375f1..c995254 100644
 47--- a/src/RawFormulas/RawFormulas.ts
 48+++ b/src/RawFormulas/RawFormulas.ts
 49@@ -27,6 +27,7 @@ import {
 50   EVEN,
 51   ERF,
 52   ERFC,
 53+  EXPONDIST,
 54   FDIST$LEFTTAILED,
 55   FINV,
 56   FISHER,
 57@@ -126,7 +127,6 @@ var EOMONTH = function (start_date, months) {
 58   var edate = moment(start_date).add(months, 'months');
 59   return new Date(edate.year(), edate.month(), edate.daysInMonth());
 60 };
 61-var EXPONDIST = Formula["EXPONDIST"];
 62 var __COMPLEX = {
 63   "F.DIST": FDIST$LEFTTAILED
 64 };
 65diff --git a/tests/FormulasTest.ts b/tests/FormulasTest.ts
 66index a10646d..8eab87a 100644
 67--- a/tests/FormulasTest.ts
 68+++ b/tests/FormulasTest.ts
 69@@ -1038,10 +1038,34 @@ catchAndAssertEquals(function() {
 70 }, ERRORS.NA_ERROR);
 71 
 72 
 73+// Test EXPONDIST
 74 assertEquals(EXPONDIST(4, 0.5, false), 0.06766764161830635);
 75+assertEquals(EXPONDIST(4, 0.5, 0), 0.06766764161830635);
 76+assertEquals(EXPONDIST(4, 0.5, true), 0.8646647167633873);
 77+assertEquals(EXPONDIST(4, 0.5, 1), 0.8646647167633873);
 78+assertEquals(EXPONDIST(4, 0.5, -1), 0.8646647167633873);
 79+assertEquals(EXPONDIST([4, "str"], ["0.5"], [false]), 0.06766764161830635);
 80+catchAndAssertEquals(function() {
 81+  EXPONDIST("str", 0.5, "1");
 82+}, ERRORS.VALUE_ERROR);
 83+catchAndAssertEquals(function() {
 84+  EXPONDIST(4, 0.5, "1");
 85+}, ERRORS.VALUE_ERROR);
 86+catchAndAssertEquals(function() {
 87+  EXPONDIST();
 88+}, ERRORS.NA_ERROR);
 89+catchAndAssertEquals(function() {
 90+  EXPONDIST(4, 0.5);
 91+}, ERRORS.NA_ERROR);
 92+catchAndAssertEquals(function() {
 93+  EXPONDIST(4, 0.5, true, 1);
 94+}, ERRORS.NA_ERROR);
 95+
 96 
 97+// Test FALSE
 98 assertEquals(FALSE(), false);
 99 
100+
101 // Test F.DIST
102 assertEquals(__COMPLEX["F.DIST"](15.35, 7, 6, false), 0.0003451054686025578);
103 assertEquals(__COMPLEX["F.DIST"](15.35, 7, 6, true), 0.9980694465675269);