diff --git a/README.md b/README.md
index 0ec4e747..b631a8b4 100644
--- a/README.md
+++ b/README.md
@@ -30,8 +30,6 @@ Implemented functions are:
     log2
     log10
     log1p
-    cis
-    cispi
     sin
     cos
     tan
diff --git a/src/Quaternion.jl b/src/Quaternion.jl
index 60a23a42..98b0db59 100644
--- a/src/Quaternion.jl
+++ b/src/Quaternion.jl
@@ -154,41 +154,6 @@ end
 _isexpfun(::Union{typeof(exp),typeof(exp2),typeof(exp10)}) = true
 _isexpfun(::Any) = false
 
-"""
-    cis(q::Quaternion)
-
-Return ``\\exp(u * q)``, where ``u`` is the normalized imaginary part of `q`.
-
-Let ``q = s + a u``, where ``s`` is the real part, ``u`` is a pure unit quaternion,
-and ``a \\ge 0`` is the magnitude of the imaginary part of ``q``.
-
-!!! Note
-    This is the extension of `cis(z)` for complex `z` to the quaternions and is not
-    equivalent to `exp(im * q)`. As a result, `cis(Quaternion(z)) ≠ cis(z)` when
-    `imag(z) < 0`.
-"""
-cis(q::Quaternion)
-
-if VERSION ≥ v"1.6"
-    """
-        cispi(q::Quaternion)
-
-    Compute `cis(π * q)` more accurately.
-
-    !!! Note
-        This is not equivalent to `exp(π*im*q)`. See [cis(::Quaternion)](@ref) for details.
-    """
-    function Base.cispi(q::Quaternion)
-        Base.depwarn("`cispi(::Quaternion)` is deprecated and will be removed in the next breaking release. See https://github.com/JuliaGeometry/Quaternions.jl/pull/76 for more information.", :cispi)
-        extend_analytic(cispi, q)
-    end
-end
-
-function Base.cis(q::Quaternion)
-    Base.depwarn("`cis(::Quaternion)` is deprecated and will be removed in the next breaking release. See https://github.com/JuliaGeometry/Quaternions.jl/pull/76 for more information.", :cis)
-    extend_analytic(cis, q)
-end
-
 for f in (
     :sqrt, :exp, :exp2, :exp10, :expm1, :log2, :log10, :log1p,
     :sin, :cos, :tan, :asin, :acos, :atan, :sinh, :cosh, :tanh, :asinh, :acosh, :atanh,
diff --git a/test/Quaternion.jl b/test/Quaternion.jl
index 12ba7c96..0d6a7e5d 100644
--- a/test/Quaternion.jl
+++ b/test/Quaternion.jl
@@ -351,7 +351,7 @@ Base.:(/)(a::MyReal, b::Real) = a.val / b
         # all complex analytic functions can be extended to the quaternions
         #! format: off
         unary_funs = [
-            sqrt, inv, exp, exp2, exp10, expm1, log, log2, log10, log1p, cis,
+            sqrt, inv, exp, exp2, exp10, expm1, log, log2, log10, log1p,
             sin, cos, tan, asin, acos, atan, sinh, cosh, tanh, asinh, acosh, atanh,
             csc, sec, cot, acsc, asec, acot, csch, sech, coth, acsch, asech, acoth,
             sinpi, cospi,
@@ -364,7 +364,7 @@ Base.:(/)(a::MyReal, b::Real) = a.val / b
             for _ in 1:100
                 c = randn(ComplexF64)
                 q = quat(c)
-                fun !== cis && @test @inferred(fun(q)) ≈ fun(c)
+                @test @inferred(fun(q)) ≈ fun(c)
                 @test q2 * fun(q) * inv(q2) ≈ fun(q2 * q * inv(q2))
             end
         end
@@ -410,8 +410,6 @@ Base.:(/)(a::MyReal, b::Real) = a.val / b
                 ]
                     @test f(q) ≈ finv(inv(q))
                 end
-                @test @test_deprecated(cis(q)) ≈ exp(normalize(q - real(q)) * q)
-                VERSION ≥ v"1.6" && @test @test_deprecated(cispi(q)) ≈ cis(π * q)
             end
         end