The main aim of the study was to evaluate the ability of TRUS to monitore hysteroscopic electroresection o submucous myomas. Of the 120 women with G0, G1 I G2 submucous myomas (by ESH) and intramural myomas enrolled in the study, 58 women underwent hysteroscopic myomectomy accompanied by intraoperative transrectal ultrasonography (the study group), whereas in 62 women the hysteroscopic myomectomy was carried out without additional methods of visualization (the control group). In both groups parameters describing the course of hysteroscopic myomectomy, complications and anatomical results were analyzed There were statistical differences in anatomical results of hysteroscopic myomectomy. One-step complete myomal resections was in 53 (91.4%) study-group cases, and in 45 (72.6%) control-group cases. Furthermore the time of hysteroscopic procedures in G2 myomas was sigificantly quicker, and the average amount of completely used medium during intramural myomas electroresection was lower in the study group. The amount of complications and conversion to other procedures although were lower in study group, but without significant difference. The transrectal intraoperative ultrasonography is a highly valuable method of hysteroscopic myomectomy monitoring, and it may significantly complement the direct endoscopic visualization of uterine cavity. Transrectal intraoperative ultrasonography optimizes parameters characterizing the course and effectiveness of the surgical procedure utilized in the removal of intramural myomas and submucous myomas with deep myometrial penetration (G2 in ESH classification).