Leiomyosarcoma in form of cyst as big as a child's head, localised at the jejunum is presented; this is a rather rare tumour and is characterised with relatively lesser malignity and rarer metastazing; it should always be treated surgically, although it grows slowly, and usually is asymptomatic, especially in the beginning when it develops intramurally, so thus bleeding can arise. The patient (a female) has been operated on urgently with a suspicion of a torsion ovarian cyst, but a tumour was found, started from the wall of the intestine itself; it was removed with the part of the wall and arising defect has been bridged by two layers stitches. The patient feels good 2 years after the operation and she will be controlled continuously.