The first attempts to systematize septal distortions have been given by Cottle who defined four groups of septal deformities: subluxation, large spurs, caudal deflection and tension septum. Fortunately, the variations of the septal deformities show a certain order, thus enabling more precise classification. Mladina was the first to make user-friendly classification of septal deformities in six basic types. He also described the seventh type, named "Passali deformity", which presents individually, but is always a well-defined combination between some of the previous six types. Mladina types of septal deformities (SD) are divided in two main groups: so called "vertical" deformities (types 1, 2, 3 and 4), and "horizontal" ones (types 5 and 6). This classification was immediately well accepted by rhinologists worldwide and started to be cited from the very beginning. Since then it has been continuously cited increasingly more often, thus making Mladina classification a gold standard whenever clinical researches on nasal septum are concerned. More than forty clinical studies based on this classification have been performed to date. It is extremely important to make a strict distinction between the types of SD since all of them play some specific role in the nasal and general physiology in man.