Limb-girdle muscular dystrophies (LGMD) are an extremely heterogeneous and rapidly expanding group of diseases characterized by progressive weakness of pelvic, scapular and trunk muscles with sparing of facial and distal musculature in most of the subtypes, onset in childhood or in adults of both sexes, very variable clinical severity ranging from mild to severe phenotypes, some associated with cardio-pulmonary and extraskeletal impairment and high serum creatine-kinase (CK) levels. In the past years, huge advances have been recorded in the various identification methods and new distinct entities were discovered. However, it is not yet clear why some muscle groups are affected and others spared in a specific subtype of LGMD, why similar clinical pictures are associated with different genes and mutations, while the same gene or mutation may present with very various clinical phenotypes. In this review we summarize the main aspects of positive and differential diagnosis in LGMD.