Abstract: The invention refers to a bodysuit used for babies or children up to 2 years old. The bodysuit consists of a fixed upper part (A) and an adjustable lower part (the panty) (B), the latter having two lateral openings (C, D) for the baby's/child's legs, bordered by two elastic strips (C1, Di) and on its backside several horizontal folds (E) created through vertical seams (F) done with elastic thread, which allow the panty to expand in length and width, depending on the baby's/child's size. Above the vertical seams there is a horizontal seam (G) done in elastic thread, which ensures the flexibility of the bodysuit in width and, furthermore, it fits the bodysuit closer to the baby's body. The bodysuit with extendible panty generates important savings in the parents' budget, as it can be used for a longer period than regular body suits, the size of the extendible panty being adjustable in length and width.