Introduction: Hypothyroidism is the most common endocrine disorder in children and presented with various sign and symptoms; its DIAGNOSIS needs a high index of suspicion.Case Presentation: We report 3 cases with unusual presentations of hypothyroidism and with delay in DIAGNOSIS that referred to Pediatric Endocrine Outpatient Clinic in Mashhad University of Medical Sciences, Mashhad, Iran with different clinical manifestations. They had decreased Thyroxin (T4) and increased thyroid stimulating hormone (TSH) levels. One case had mental retardation and deafness, but the other two cases had normal neurodevelopment. Some additional interesting findings were as follows: short stature, DELAYED bone age, teeth eruption impairment, hair loss, anemia and hypercholesterolemia, persistent and long-term constipation that had led to several abdominal surgeries. After a year of hormonal replacement therapy, their growth parameters and hematological values improved.Conclusions: We recommend thyroid hormonal evaluation for any children with short stature, especially with DELAYED bone age, in order to detect and treat hypothyroidism at the right time. It seems that more attention to pediatric growth is necessary.