Background: Formalin and hexamine as important chemicals are widely used in industry that their pollution effect is often taken into account. The aim of this study was to investigate environmental effects of formalin and hexamine production process in Gameron Petro Industry Complex using the life cycle assessment method. Methods: This study was conducted according to ISO 14040, using the life cycle assessment (LCA) method and SimaPro software 9, as well as Eco-indicator99, IMPACT2002+ and EDIP2003. The functional unit studied was 1 ton of product (800 kg hexamine plus 200kg formalin) in this complex. Results: It was found that ammonia was the most influential input material in creating the consequences of climate change, radiation and toxicity. In respiratory inorganics, the contribution of ammonia and methanol was the same. Methanol was the dominant input of other outcome. It was determined that the effect of methanol and ammonia on human health was approximately equal. Ammonia and methanol had effect on ecosystem toxicity and creating the category of resource consumption, respectively. The total values of the effect classes were 0.001636 DALY, 2038.305 PDF.m² yr, 2091.536 kg CO2 equivalents and 61.87139MJ surplus. Conclusion: The results showed that in the life cycle of formalin production, and hexamine, methanol is the dominant input in creating environmental impacts. After that, ammonia, diesel and electricity were the effective inputs in the production life cycle of these products.