Abstract: Tea soils are enriched with more amount of Fe and the soils of tea plantations are continuously saturated with water for several weeks. This leads to depletion in oxygen, causes reduction in oxidation process and enhances the reduction process. During reduction process all the Fe3+ ions are reduced to Fe2+ which is the more favored form for plant uptake. This increase in uptake of Fe2+ ion may cause changes in the biochemical constituents and disturbs the enzyme activity. So the necessity occurs to study the impact of excess iron on biochemical parameters and enzyme activity in tea plant. The study was conducted at nursery level using one year old plant of clone UPASI 9 under green house condition. The chlorophyll and polyphenols content increased with the addition of smaller amount of iron, a sharp decline was noted with increase in iron dosage. This is proved by the negative and significant correlation coefficient obtained between soil applied Fe and leaf polyphenols (r = -0.801 p = 0.05). The activity of invertase was higher even at higher dosage whereas the amylase activity decreases with increase in iron concentration. It was found that the glutamate synthase activity and amino acid content decreases sharply with increase in iron addition. The decrease in glutamate synthase activity and amino acid content proves that excess iron influence the nitrogen metabolism leading to lack of nitrogen assimilation in tea plant which ultimately reflects on productivity. Even though iron increases the activity of enzymes like amylase, invertase and biochemical parameters to certain extent, at higher concentration it was found harmful to plants leading to plant death.