diff --git a/pytorch_toolbox/probe/gradient_probe.py b/pytorch_toolbox/probe/gradient_probe.py
new file mode 100644
index 0000000..4c0ce00
--- /dev/null
+++ b/pytorch_toolbox/probe/gradient_probe.py
@@ -0,0 +1,68 @@
+'''
+Simple way to monitor/manipulate gradient.
+
+Usage:
+  gradient_record = GradientRecordHook(name='record')
+  gradient_scale = GradientScale(name='scale')
+  def net.forward(input):  # your forward function
+    fc = base_layers(input)
+    # Check gradient:
+    fc = gradient_record(fc)
+    # invert gradient (e.g. domain adapt.)
+    fc = gradient_scale(fc, -1)
+    output = estimator_layers(fc)
+  Afterwards, we can plot these records to check the gradient.  
+'''
+import torch
+
+
+class GradientScaleFunction(torch.autograd.Function):
+    @staticmethod
+    def forward(ctx, x, lambda_):
+        ctx.lambda_ = lambda_
+        return x.clone()
+
+    @staticmethod
+    def backward(ctx, grads):
+        lambda_ = ctx.lambda_
+        lambda_ = grads.new_tensor(lambda_)
+        dx = lambda_ * grads
+        return dx, None
+
+
+class GradientScale(torch.nn.Module):
+    def __init__(self, name=None):
+        super(GradientScale, self).__init__()
+        self.name = name
+        self.lambdar = 0
+
+    def forward(self, x, lambdar):
+        self.lambdar = lambdar
+        return GradientScaleFunction.apply(x, lambdar)
+
+
+class GradientRecordHook(torch.nn.Module):
+    '''
+    Simple way to record gradient
+    '''
+
+    def __init__(self, name=None):
+        super(GradientRecordHook, self).__init__()
+        self.lambdar = 0
+        self.gradients = []
+        self.mag = None
+        self.std = None
+        self.name = name
+
+    def hook_fun(self, grad):
+        self.mag = torch.mean(torch.abs(grad)).item()
+        self.std = torch.std(grad).item()
+
+    def forward(self, x):
+        '''
+        Do Nothing
+        '''
+        if self.training:
+            x.register_hook(self.hook_fun)
+        return x
+