In 28 children with persistent toe-walking, in whom no etiologic diagnosis was evident from the beginning, we have studied peri- and postnatal history, details of locomotor development and the evolution of the symptom (toe-walking). A detailed neurological and orthopaedic examination was performed. Four main groups could be identified: 1. minimal spastic diplegia (5 children), 2. habitual toe-walking (9 children), 3. congenital short tendo calcaneus (4 children), 4. mixed or unclassified (10 children). A detailed reevaluation of this latter group has enabled us to reclassify them in one of the three major categories even if in certain cases several factors seemed to play a role in the toe-walking. Diagnostic criteria, the evolution and consequences of the symptom, and the familial aspect are discussed. Regarding habitual toe-walking, the history of pre-walking locomotor development, the characteristics of behaviour and the knowledge of normal development of independent gait do not offer a general explanation for this particular motor behaviour.