diff --git a/CombineTools/interface/CombineHarvester.h b/CombineTools/interface/CombineHarvester.h
index 1f6403bc687..a4f87c7784f 100644
--- a/CombineTools/interface/CombineHarvester.h
+++ b/CombineTools/interface/CombineHarvester.h
@@ -337,6 +337,7 @@ class CombineHarvester {
    */
   /**@{*/
   double GetRate();
+  std::map<std::string, double> RateEvolution(RooFitResult const& fit);
   double GetObservedRate();
   double GetUncertainty();
 
diff --git a/CombineTools/src/CombineHarvester_Evaluate.cc b/CombineTools/src/CombineHarvester_Evaluate.cc
index 6a6dea751a4..dee308f46cd 100644
--- a/CombineTools/src/CombineHarvester_Evaluate.cc
+++ b/CombineTools/src/CombineHarvester_Evaluate.cc
@@ -580,6 +580,36 @@ void CombineHarvester::UpdateParameters(RooFitResult const* fit) {
   UpdateParameters(*fit);
 }
 
+std::map<std::string, double> CombineHarvester::RateEvolution(RooFitResult const& fit) {
+  auto lookup = GenerateProcSystMap();
+  std::map<std::string, double> rates;
+  auto backup = GetParameters();
+  rates["prefit"] = GetRateInternal(lookup);
+  for (int i = 0; i < fit.floatParsFinal().getSize(); ++i) {
+    RooRealVar const* var =
+        dynamic_cast<RooRealVar const*>(fit.floatParsFinal().at(i));
+    // check for failed cast here
+    auto it = params_.find(std::string(var->GetName()));
+    if (it != params_.end()) {
+      it->second->set_val(var->getVal());
+      it->second->set_err_d(var->getErrorLo());
+      it->second->set_err_u(var->getErrorHi());
+    } else {
+      if (verbosity_ >= 1) {
+        LOGLINE(log(),
+                "Parameter " + std::string(var->GetName()) + " is not defined");
+      }
+      continue;
+    }
+    double rate = GetRateInternal(lookup);
+    // std::cout << "\t" << it->first << "\t" << rate << std::endl;
+    rates[it->first] = rate;
+    // reset parameters to prefit conditions
+    this->UpdateParameters(backup);
+  }
+  return rates;
+}
+
 std::vector<ch::Parameter> CombineHarvester::GetParameters() const {
   std::vector<ch::Parameter> params;
   for (auto const& it : params_) {
diff --git a/CombineTools/src/CombineHarvester_Python.cc b/CombineTools/src/CombineHarvester_Python.cc
index 93002b02a8d..aa1787f4dc9 100644
--- a/CombineTools/src/CombineHarvester_Python.cc
+++ b/CombineTools/src/CombineHarvester_Python.cc
@@ -232,6 +232,9 @@ BOOST_PYTHON_MODULE(libCombineHarvesterCombineTools)
   py::to_python_converter<std::map<std::string, CombineHarvester>,
                           convert_cpp_map_to_py_dict<std::string, CombineHarvester>>();
 
+  py::to_python_converter<std::map<std::string, double>,
+                          convert_cpp_map_to_py_dict<std::string, double>>();
+
   py::to_python_converter<TH1F,
                           convert_cpp_root_to_py_root<TH1F>>();
 
@@ -338,6 +341,7 @@ BOOST_PYTHON_MODULE(libCombineHarvesterCombineTools)
       // Modification
       .def("GetParameter", Overload1_GetParameter,
         py::return_value_policy<py::reference_existing_object>())
+      .def("RateEvolution", &CombineHarvester::RateEvolution)
       .def("UpdateParameters", Overload1_UpdateParameters)
       .def("RenameParameter", &CombineHarvester::RenameParameter)
       .def("RenameSystematic", &CombineHarvester::RenameSystematic)