We have examined 20 tongue-tie patients who had been operated the lingual frenectomy in Dept. of Oral & Maxillofacial surgery, Pusan National University for the effect of the lingual frenectomy on the tongue motion and speech, and divided patients into groups by age. Each group was separated as follows ; the age of 5-6, 7-9, 10-12, 13-15, and 16-18. We measured the frenal lengh, the range of tongue motion and evaluated the speech pre- and postoperatively. The preoperative patient groups have larger tongue tips and smaller lingual frenums than normal ones. In the preoperative patient group, there was significant obstacle of the protrusive and superior movement of the tongue. The exception was the laterotrusive movement on both sides. There was the lower value of the Picture Consonant Articulation Test(PCAT) in the preoperative 5 to 6 year-old group compared with normal group. In other age groups, there was no significant difference. The range of postoperative PCAT in all age groups has become as similiar as that of normal group. The 5 to 6 year-old group which had significant difference in PCAT was improved in PCAT. In conclusion, we propose that the PCAT as well as anatomical tongue size and functional tongue movement is the basis of the indication of lingual frenectomy and the 5-6 year-old is the optimal time of the lingual frenectomy for improvement of the tongue movement and the speech.