BACKGROUND: Bovine coronavirus (BCoV) is a primary cause of neonatal calf diarrhea worldwide, and is also associated with acute diarrhea in adult cattle during the winter season, resulting heavy economic losses to both dairy and beef industry throughout the world. OBJECTIVE: The Objective of the present study was to screen the fecal samples for BCoV collected from diarrhea from six geographic region of Iran, with the aim to deepen the knowledge of BCoV prevalence and epidemiology in Iran. MEETHODS: 194 fecal samples from diarrheic calves up to one-month age, based on the geographic area were collected. Samples from all the cases were screened for the presence of BCoV by commercially available ELISA kit. Furthermore, all positive samples were subjected to RT-PCR for confirmation. RESULTS: ELISA examination revealed that 7.2 % of taken samples, were positive. All positive samples in ELISA were also positive in RT-PCR. All samples from northwest, northeast, and west, were negative. The average ages of positive calves were nine days. The average stool scores in positive samples and negative samples were 2.5 and 2.1 respectively. 71/4 % of positive samples had fever. CONCLUSION: The results of the present study showed that the occurrence of BCoV in stool samples of diarrheic calves in dairy farms of Iran is lower than the other reports on the world.