The aim of the present prospective study was to evaluate the functional sequelae and postoperative development of quality of life after intraoral tumour surgery in 40 consecutive patients with a squamous cell carcinoma of the floor of the mouth. Immediate reconstruction of intraoral soft tissues after tumour resection was accomplished by local flaps (cheek and tongue) (n = 27) and by revascularized transfer of small bowel grafts (n = 5) and myocutaneous/fasciocutaneous flaps (n = 8). Mobility of the tongue was assessed by ultrasound. Quality of speech was analysed using the Freiburg speech intelligibility test. Life quality was assessed by the functional living index-cancer preoperatively and six months postoperatively. A significant decrease in both mobility of the tongue and quality of speech was registered. The most substantial effect on quality of speech resulted from decreased movement of the base and the dorsum of the tongue. A significant increase in life quality at the end of the study period occurred only in the group of patients without substantial reduction of intelligibility of speech, while no significant improvement of postoperative life quality of patients with more severe deterioration of speech quality was found.