diff --git a/src/LSHFunctions.jl b/src/LSHFunctions.jl
index 0c95055..b1f33ac 100644
--- a/src/LSHFunctions.jl
+++ b/src/LSHFunctions.jl
@@ -36,7 +36,7 @@ Exports
 ========================#
 
 # Similarity functions, norms, inner products
-export cossim, inner_prod, ℓ1, ℓ2, ℓp, L1, L2, Lp, ℓ1_norm, ℓ2_norm,
+export cossim, hamming, inner_prod, ℓ1, ℓ2, ℓp, L1, L2, Lp, ℓ1_norm, ℓ2_norm,
        ℓp_norm, L1_norm, L2_norm, Lp_norm, jaccard
 
 # Hash functions
diff --git a/src/similarities.jl b/src/similarities.jl
index cdf002d..2e5cac0 100644
--- a/src/similarities.jl
+++ b/src/similarities.jl
@@ -11,6 +11,48 @@ using LinearAlgebra: dot, norm
 Definitions of built-in similarity functions
 ====================#
 
+#====================
+Hamming distance
+====================#
+
+@doc raw"""
+    hamming(x,y)
+
+Computes the Hamming distance between two bit vectors ``x`` and ``y``. Hamming distance is defined as the number of locations in which ``x`` and ``y`` disagree, i.e.
+
+``\text{Hamming}(x,y) = \sum_i |x_i - y_i|``
+
+# Arguments
+- `x::Union{BitArray{1},Vector{Bool}}`, `y::Union{BitArray{1},Vector{Bool}}`: the two bit vectors between the Hamming distance is computed.
+
+# Examples
+```jldoctest; setup = :(using LSHFunctions)
+julia> x = BitArray([1, 0, 1, 1]);
+
+julia> y = BitArray([0, 0, 1, 0]);
+
+julia> hamming(x,y)
+2
+```
+"""
+function hamming(
+    x::Union{BitArray{1}, Vector{Bool}},
+    y::Union{BitArray{1}, Vector{Bool}}
+)
+    if length(x) != length(y)
+        "Lengths of x and y are not equal ($(length(x)) != $(length(y))" |>
+        ErrorException |>
+        throw
+    end
+
+    total = 0
+    @inbounds @simd for ii = 1:length(x)
+        total += (x[ii] != y[ii])
+    end
+
+    return total
+end
+
 #====================
 Cosine similarity
 ====================#
diff --git a/test/test_similarities.jl b/test/test_similarities.jl
index d23fe97..328fb5d 100644
--- a/test/test_similarities.jl
+++ b/test/test_similarities.jl
@@ -7,6 +7,18 @@ include("utils.jl")
 Tests
 ==================#
 
+@testset "Hamming distance tests" begin
+    @testset "Calculate Hamming distances between bit vectors" begin
+        x = BitArray([1, 1, 0, 1, 0, 1, 0, 1])
+        y = BitArray([1, 1, 1, 1, 0, 0, 0, 1])
+        z = BitArray([1, 1, 1, 0, 1, 1, 1, 0])
+
+        @test hamming(x, y) == 2
+        @test hamming(x, z) == 5
+        @test hamming(y, z) == 5
+    end
+end
+
 @testset "ℓ^p distance and norm tests" begin
     Random.seed!(RANDOM_SEED)