Background: Seborrheic dermatitis is chronic disease and in some cases despite an appropriate treatment, symptoms continue, therefore the aim of this study was evaluation of the effectiveness of topical zinc acetate in treatment of seborrheic dermatitis. Methods: This was a single blinded randomized clinical trial and study population consisted of 60 patients with seborrheic dermatitis in face or skull referring to dermatology clinics affiliated to Isfahan University of Medical Sciences, Isfahan, Iran. Patients were divided to two groups; first groups received Ketoconazole 2% solution and a placebo solution while the second group received both ketoconazole 2% solution and zinc acetate 1.2% solution. After collecting data, SPSS software was used for data analysis via t test and chi-square. Findings: The results of this study shows this medication significantly improved pruritus but was ineffective for erythema. Before this test, pruritus in case group was 2.63±2.41 and in control group was 2.57±2.35 and after treatment pruritus in case group was 1.05±0.70 and in control group was 1.59±1.07, which according to the test, significant difference was observed between groups using chi-square test (P<0.05). Before test, erythema in case group was 1.23±0.43 and in control group was 1.07±0.58 and after treatment in case group was 0.63±0.66 and in control group was 0.66±0.62, there was no significant difference between the two groups (P>0.05). Conclusion: The results of this study encourage using zinc acetate1.2% in the treatment of seborrheic dermatitis so we can improve the quality of life of patients by decreasing pruritus and also this study suggests to measure other effects of zinc acetate on other symptoms such as Scaling.