THIS STUDY AIMED TO ASSESS THE ENVIRONMENTAL IMPACT OF Cast IRON INDUSTRIES USING TOPSIS AND FUZZY TOPSIS WAS DONE. IN THE SAME WAY, PARS SAVEH Cast IRON INDUSTRIES, 10 KM NORTH OF SAVEH CUNTY WAS CHOSEN AS A CASE STUDY. IN THIS STUDY, IN ASSESSING THE ENVIRONMENTAL IMPACTS TOPSIS AND F-TOPSIS, MULTICRITERIA DECISION MODELS, WERE USED. RESULTS FROM RANKING OF IMPACT IN THIS STUDY SHOWN THAT IN BOTH METHODS, REDUCED AIR QUALITY WITH SIMILARITIES INDEX EQUAL TO 0.748 AND CLI EQUAL TO 0.743; DECLINE IN GROUNDWATER LEVEL WITH SIMILARITIES INDEX EQUAL TO 0.737 AND CLI EQUAL TO 0.548 AND INCREASED LEVELS OF NOISE AND VIBRATION WITH SIMILARITIES INDEX EQUAL TO 0.732 AND CLI EQUAL TO 0.529 ALL THREE WITH NEGATIVE NATURE ARE RATINGS ON FIRST AND THIRD. IN TOPSIS METHOD CREATE JOBS AND PROSPERITY, CLI EQUAL TO 0.436 WITH POSITIVE NATURE AND RESPIRATORY DISORDERS CLI EQUAL TO 0.429 WITH NEGATIVE NATURE; AND IN F-TOPSIS, EYE DISEASES WITH SIMILARITIES INDEX EQUAL TO 0.732 AND DISRUPTION IN WILDLIFE MIGRATION WITH SIMILARITIES INDEX EQUAL TO 0.731 BOTH WITH NEGATIVE NATURE ARE THE FOURTH AND FIFTH. THE ADVANTAGE OF TOPSIS IN THE ENVIRONMENTAL IMPACTS ASSESSMENT IS RANKING POSITIVE AND NEGATIVE IMPACTS BY USING DIFFERENT CRITERIA. WHEN JUDGMENTS AND OPINIONS ARE VAGUE AND INACCURATE, F-TOPSIS IS THE PREFERRED TECHNIQUE.