Background: Although ventricular septal defect (VSD) is the most common congenital heart disease, it is usually diagnosed late. The picture of the disease is variable; sometimes it is so quiet and silent that it could even heal and improve spontaneously, and in some cases if the appropriate, timely and early treatment is not carried out, this would lead to irreparable complications even in the early periods of life such as mortality. This study aimed to study, review and process way of diagnosis, treatment and follow-up of these patients. It is hoped that the results of the present study will be used to improve patient conditions. Methods: This was a cross-sectional study conducted on 145 patients with VSD during 54 months in Isfahan. The required data is collected at the time of definitive diagnosis by taking their medical history. The disease was identified by color Doppler echocardiography and, if necessary, cardiac catheterization and angiography. Results: The mean age of initial disease diagnosis was 17 months and the mean age of definitive diagnosis was 44 months. The initial diagnosis in 85% of cases was associated with a heart murmur. In 27.5% of cases, VSD was associated with other cardiac anomalies. Pulmonary arterial hypertension was observed in 16.5% of cases. 59 surgeries were performed on 40 patients. Conclusion: In the daily and routine examination of newborns, the probability of heart disease should be considered; performing an echocardiogram and a cardiological examination in suspected cases would lead to early diagnosis and ultimately timely treatment. Adequate follow-up of patients will lead to the provision of optimal care and treatment services at the heart of the paper and ultimately the treatment of heart disease. Considering the possibility of additional cardiac abnormalities and even pulmonary arterial hypertension would provide optimal care and treatment services at the right time. References…Table 1: The type of VSD and additional cardiac anomalies, pulmonary arterial hypertension (PAH), number and age of surgery in studied patients. type of VSD Number (percentage) No. PAH (%) No. of surgery ( %) Age at surgery (month)Single VSD 105 (72.5) 8 (7.6) 15 (14) 45 ± 22VSD with additional cardiac anomalies 40 (27.5) 16 (40) 19 (47.5) 37 ± 14Patent ductus arteriosus 20 (50) 11 (55) 19 (95) 10 ± 3Patent ductus arteriosus with aortic coarctation 6 (15) 5 (83) 5 (83 ) 10 ± 3Atrial perforation 5 (12.5) - 1 ( 20) 44 ± 29 Pulmonary artery stenosis 9 (22.5) - -Bacterial endocarditis 1 (0.7) Mortality 2 (1.4)