diff --git a/src/decagon_pytorch/splits.py b/src/decagon_pytorch/splits.py
new file mode 100644
index 0000000..e0394cc
--- /dev/null
+++ b/src/decagon_pytorch/splits.py
@@ -0,0 +1,26 @@
+import torch
+
+
+def train_val_test_split_adj_mat(adj_mat, train_ratio, val_ratio, test_ratio):
+    if train_ratio + val_ratio + test_ratio != 1.0:
+        raise ValueError('Train, validation and test ratios must add up to 1')
+
+    edges = torch.nonzero(adj_mat)
+    order = torch.randperm(len(edges))
+    edges = edges[order, :]
+    n = round(len(edges) * train_ratio)
+    edges_train = edges[:n]
+    n_1 = round(len(edges) * (train_ratio + val_ratio))
+    edges_val = edges[n:n_1]
+    edges_test = edges[n_1:]
+
+    adj_mat_train = torch.zeros_like(adj_mat)
+    adj_mat_train[edges_train[:, 0], edges_train[:, 1]] = 1
+
+    adj_mat_val = torch.zeros_like(adj_mat)
+    adj_mat_val[edges_val[:, 0], edges_val[:, 1]] = 1
+
+    adj_mat_test = torch.zeros_like(adj_mat)
+    adj_mat_test[edges_test[:, 0], edges_test[:, 1]] = 1
+
+    return adj_mat_train, adj_mat_val, adj_mat_test
diff --git a/tests/decagon_pytorch/test_splits.py b/tests/decagon_pytorch/test_splits.py
new file mode 100644
index 0000000..79482fb
--- /dev/null
+++ b/tests/decagon_pytorch/test_splits.py
@@ -0,0 +1,95 @@
+from decagon_pytorch.data import Data
+import torch
+from decagon_pytorch.splits import train_val_test_split_adj_mat
+import pytest
+
+
+def _gen_adj_mat(n_rows, n_cols):
+    res = torch.rand((n_rows, n_cols)).round()
+    if n_rows == n_cols:
+        res -= torch.diag(torch.diag(res))
+        a, b = torch.triu_indices(n_rows, n_cols)
+        res[a, b] = res.transpose(0, 1)[a, b]
+    return res
+
+
+def train_val_test_split_1(data, train_ratio=0.8,
+    val_ratio=0.1, test_ratio=0.1):
+
+    if train_ratio + val_ratio + test_ratio != 1.0:
+        raise ValueError('Train, validation and test ratios must add up to 1')
+
+    d_train = Data()
+    d_val = Data()
+    d_test = Data()
+
+    for (node_type_row, node_type_col), rels in data.relation_types.items():
+        for r in rels:
+            adj_train, adj_val, adj_test = train_val_test_split_adj_mat(r.adjacency_matrix)
+            d_train.add_relation_type(r.name, node_type_row, node_type_col, adj_train)
+            d_val.add_relation_type(r.name, node_type_row, node_type_col, adj_train + adj_val)
+
+
+def train_val_test_split_2(data, train_ratio, val_ratio, test_ratio):
+    if train_ratio + val_ratio + test_ratio != 1.0:
+        raise ValueError('Train, validation and test ratios must add up to 1')
+    for (node_type_row, node_type_col), rels in data.relation_types.items():
+        for r in rels:
+            adj_mat = r.adjacency_matrix
+            edges = torch.nonzero(adj_mat)
+            order = torch.randperm(len(edges))
+            edges = edges[order, :]
+            n = round(len(edges) * train_ratio)
+            edges_train = edges[:n]
+            n_1 = round(len(edges) * (train_ratio + val_ratio))
+            edges_val = edges[n:n_1]
+            edges_test = edges[n_1:]
+            if len(edges_train) * len(edges_val) * len(edges_test) == 0:
+                raise ValueError('Not enough edges to split into train/val/test sets for: ' + r.name)
+
+
+def test_train_val_test_split_adj_mat():
+    adj_mat = _gen_adj_mat(50, 100)
+    adj_mat_train, adj_mat_val, adj_mat_test = \
+        train_val_test_split_adj_mat(adj_mat, train_ratio=0.8,
+            val_ratio=0.1, test_ratio=0.1)
+
+    assert adj_mat.shape == adj_mat_train.shape == \
+        adj_mat_val.shape == adj_mat_test.shape
+
+    edges_train = torch.nonzero(adj_mat_train)
+    edges_val = torch.nonzero(adj_mat_val)
+    edges_test = torch.nonzero(adj_mat_test)
+
+    edges_train = set(map(tuple, edges_train.tolist()))
+    edges_val = set(map(tuple, edges_val.tolist()))
+    edges_test = set(map(tuple, edges_test.tolist()))
+
+    assert edges_train.intersection(edges_val) == set()
+    assert edges_train.intersection(edges_test) == set()
+    assert edges_test.intersection(edges_val) == set()
+
+    assert torch.all(adj_mat_train + adj_mat_val + adj_mat_test == adj_mat)
+
+    # assert torch.all((edges_train != edges_val).sum(1).to(torch.bool))
+    # assert torch.all((edges_train != edges_test).sum(1).to(torch.bool))
+    # assert torch.all((edges_val != edges_test).sum(1).to(torch.bool))
+
+
+@pytest.mark.skip
+def test_splits_01():
+    d = Data()
+    d.add_node_type('Gene', 1000)
+    d.add_node_type('Drug', 100)
+    d.add_relation_type('Interaction', 0, 0,
+        _gen_adj_mat(1000, 1000))
+    d.add_relation_type('Target', 1, 0,
+        _gen_adj_mat(100, 1000))
+    d.add_relation_type('Side Effect: Insomnia', 1, 1,
+        _gen_adj_mat(100, 100))
+    d.add_relation_type('Side Effect: Incontinence', 1, 1,
+        _gen_adj_mat(100, 100))
+    d.add_relation_type('Side Effect: Abdominal pain', 1, 1,
+        _gen_adj_mat(100, 100))
+
+    d_train, d_val, d_test = train_val_test_split(d, 0.8, 0.1, 0.1)