Background. Iodine is an essential element for thyroid hormone synthesis important for growth and development. An Epidemiological study is important to describe who the case were, area mostly affected and trends of disease over time. Objective. The purpose of this study was to describe the epidemiological characteristics of patients with thyroid dysfunction. Method. This is a descriptive study. Data taken from medical record of 291 patients with hypothyroidism and hyperthyroidism diagnoses from Klinik Litbang GAKI Magelang in 2011-2012. Medical records used were the one that recorded age and gender, address and time of diagnose. The differences characteristic comparation of hypothyroidism and hyperthyroidism were analyzed using Chi Square. Results. Result found that hypothyroidism affected younger (<20 years) patients while hyperthyroidism affected older (20-39 years), p=0.00. Women suffered thyroid dysfunction more than men with 58.8% hypothyroidism and 88.35% hyperthyroidism, p=0.00. Patients with hypothyroidism and hyperthyroidism came from areas with history of mild endemic area (p=0.247). The trend showed that hypothyroidism and hyperthyroidism increase from 2011 to 2012, although not statistically significant (p=0.194). Conclusion. Hypothyroidism and hyperthyroidism are more common in female. Hyperthyroidism affected older age group compare to hypothyroidism. Both hypothyroidism and hyperthyroidism more prevalent on patient came from areas with history of mild endemic and showed increasing trend.