Pilonidal sinus is a not infrequent disease, probably due to a disontogenetic origin. Histologically, there is a pseudocystic formation in the subcutaneous adipose tissue, containing some hair bulbs. It usually presents a recurring inflammatory course. The pathologic formation does not normally have thick wall, being made up of thin epidermal epithelium, without internal vascularisation and with frequent subcutaneous fistulae. Even though the clinical diagnosis is rather easy, surgery may prove, on the contrary, a demanding task, with a high incidence of recurrence and complications. An adequate knowledge of the condition and its development, with a precise definition of the margins of the lesions, may simplify the surgery, reducing the chance of recurrence or complications. The use of echography in the diagnosis of this disease, in our cohort of 72 patients, has always provided valuable information. In particular, 13 and 18 MHz linear probes and 20 MHz mechanical array have been used, and the latter in particular for the evaluation of fistolous cavities/passageways under the skin. Results. In all our cases, echography has demonstrated pseudocystic formations, without real walls, with fairly high levels of internal echoes, compared to the hair follicles, or, more rarely, true macrocalcifications with one or more cavities/passageways near the skin, without internal vascularisation, according to the histological findings. Echographic data are rapidly obtained, and can prove useful for surgeons for a a better management of patients. Conclusion. We consider diagnostic echography, using high frequency probes, useful for the anatomical definition of this disease, as well as to enable better surgical management.