Background: Congenital myopathies (CM) are inherited muscle disorders historically classified according to features seen on muscle biopsy and congenital-onset weakness and hypotonia. The aim of our study was to evaluate the benefit of genetic testing, muscle biopsy, NCS/EMG and muscle MRI in obtaining a definite diagnosis for these patients. Methods: A retrospective chart review of all patients diagnosed at a single tertiary-care pediatric hospital over 15 years (2008-2022). REB approval was obtained. Results: Over a period of 15 years, 42 patients with CM were included. All (100%) had genetic testing (i.e. gene panel, WES), 65.9% had muscle biopsy, 67.5% had NCS/EMG and 20% had a muscle MRI. Definite diagnosis was obtained in 38% by genetic testing only, while 42.8% had a diagnosis made by genetic testing supported by the findings of one or more of the other diagnostic tools. Conclusions: Early diagnosis of CM is still essential in congenital myopathies to provide optimal care. Genetic testing is the gold standard for diagnosis, but other diagnostic tools remain valuable in the case of variants of unclear significance.