There are several methods to reduce serum bilirubin in neonatal jaundice that the most common of them is phototherapy and this method will cause some side effects which one of them is hypocalcemia that is occurred due to the decreased serum concentration of melatonin. This study was conducted aims to evaluate the effect of covering head on hypocalcemia caused by the phototherapy in the icteric infants in the Vali-e-Asr Hospital in 2015. in this clinical trial study, 60 preterm infants with icterus characteristics were hospitalized in NICU ward of Vali-e-Asr Hospital in Birjand at 2014 that had the inclusion criteria and were selected by available sampling and divided into two test group (30 individuals) and control group (30 individuals). Infants of the control group with the routine method and infants of the test group with the use of a hat covering occiput were treated under phototherapy. Serum bilirubin and calcium were checked upon admission, 48 hours after starting phototherapy and 24 hours after discontinuation of phototherapy. Data were analyzed using the statistical software of SPSS 15 and statistical t-test at the significance level of 0.05. results showed that the average age at birth, age at phototherapy, average of bilirubin level and calcium level before intervention in the infants of both test and control groups did not have a significant difference (P>0.05). But 48 hours after starting phototherapy, the average of serum calcium in the infants of test group compared to the control group and 24 hours after discontinuation of phototherapy in the infants of control group was significantly higher (P<0.05). In other words, incidence of hypocalcemia in infants with phototherapy with hat was significantly lower than infants with routine phototherapy. In this study (53 percent) of infants of the control group received 58.9 mg intravenous calcium. Only 6% of the infants in the intervention group received 10 mg intravenous calcium. covering the head of infants under phototherapy is an effective, safe and low cost method to prevent hypocalcemia.