**1. Introduction**

Skin biopsy is a fundamental method to correct diagnosis in lots of skin diseases. To make a "good use" of it, it is necessary to know at what time, to whom it can be done, how many biopsies, and principally in which sites can be applied.

Once choosing the biopsy site, it must be taken into account several factors that depend on the patient and the type of lesion concerned. Also, it should be considered the elementary type of lesion, the depth of it, and the indemnity of the skin as well as other factors.

Within the type of lesions, there are certain diseases that have special features when the physician decide make biopsy such as pigmented lesions and alopecia.

The skin biospies are extremely useful not only for diagnosis, but also for monitoring, therapy evaluation and sometimes they are the treatment itself for certain skin diseases.

In recent times there have been studies that are used in skin biopsies for the diagnosis and /or follow up of non-dermatological diseases, such as neuropathies and intravascular lymphoma B cells. In these diseases there are not typical or no typical cutaneous lesions. Therefore, it is in these cases when we ask where it would be the most suitable site to take the biopsy.
