Thyroid dysfunction is common in the population, especially in women, and thyroid diagnostic tests are among the most often used diagnostic procedures nowadays. Many thyroid societies developed guidelines for the detection of thyroid dysfunction. An interdisciplinary team of experts from the Croatian Thyroid Society studied guidelines of other thyroid societies and international publications, and according to our tradition and clinical practice developed guidelines for rational detection of thyroid dysfunction; hypothyroidism and hyperthyroidism. The aim of these guidelines is to recommend evidence-based and rational approach to the detection of thyroid dysfunction.