The increasing knowledge about limb girdle muscular dystrophy (LGMD) has clarified many aspects of this extensive group of neuromuscular conditions and has moreover proven their wide clinical and genetic heterogeneity. For these reasons, achieving a precise diagnosis of a particular type of LGMD may be still difficult and requires a comprehensive approach, which includes epidemiology, medical history, clinical examination, laboratory and genetic tests. All of the LGMDs are individually rare and their population frequency is highly variable. The prevalence of the different forms of LGMD in different populations has to be considered for the differential diagnosis. Some characteristic clinical features may help to distinguish subtypes of LGMD however protein analysis on muscle biopsy and genetic testing still represent the gold standard in the diagnosis of these muscular dystrophies. Reaching a precise diagnosis in all patients is important to allow genetic counseling to be properly applied and to direct appropriate medical management with a potential positive impact on the length and quality of life. Moreover, new specific therapeutic approaches, including limited local gene therapy, have been emerging over the last few years and require a precise genetic definition of the conditions. This article will concentrate on the diagnostic process by which these disorders can be defined and the implications of making these diagnoses.