Background: Failure to thrive is slow physical development in a baby or child. It’s caused by a baby or child not having enough nutrition .The aim of the study is to find association between failure to thrive (FTT) and Congenital Heart Disease(CHD) in newborns/infants. Material & Methods: This was a Cross-sectional observational study included children age between 0 to 1 year with suspected heart disease came to outdoor and indoor services of Department of Pediatrics IGMC , Shimla from July 2018 to June 2019. Results: In our study there were 102 participants in total. Out of them 57 participants were ≤1 month of age i.e. 57(55.90 % of total, 29(28.4%) between 2-6 months,16(15.7%) between 7-12 months. There were 55 males and 47 females. In the present study, Failure to thrive was present in 17 (16.7%) out of 102 study participants. Failure to thrive was seen in 16 patients among all 79 diagnosed patients with CHD. Odd ratio was 0.22 with CI (0.03-1.57), with P value of 0.14, which is not significant. The sensitivity ,specificity , positive predictive value(PPV) and negative predictive value(NPV) of failure to thrive in diagnosing CHD is 20.2 % , 95.6% , 94.1 % and 25.88% respectively Conclusion: It is important to determine whether failure to thrive results from congenital heart disease or factors in the environment, such as abuse or neglect.