An experimental study was done for the appearance of tissue mast cells in tongue, cheek, trachea, and lung. These were made after complete closure (suture) of left anterior nostril only and both anterior nostril together with follow up after various intervals. For the experimental animals, the healthy albino-rats weighing between 120 to 130 gms, were used. They were divided into following several groups according to various experimental procedures. I. Normal group : no procedure applied. II. Control group : preoperative procedure as needle penetration on the nostril, but without suture. III. Experimental group : 1) 5 hour complete closure of left nostril. 2) 5 hour complete bilateral closure of nostril. 3) 48 hour complete closure of left nostril. 4) 48 hour complete bilateral closure of nostril. After above various procedures, the animals were sacrified with intervals of 0, 1, 3, 6, 12, 24, 48, 72 hours. The paraffin sections were prepared and stained with Toludine Blue to demonstrate the tissue mast cells. The above cell count was done under 20 high power fields in each section and compared through different parts. The results of the study are summerized as follows : 1) The tissue mast cells of various tissues decreased nummerically a minimum between 0 to 3 hours over all groups except normal group. 2) The tissue mast cells of various tissues increased between minimum 3 hours to maximum 24 hours and reached normal range at 48 hours. 3) In the control group, the above tissue mast cells were slightly decreased a minimum between 0 to 3 hours and recoverd between 3 to 24 hours. 4) In the right lung, the change of tissue mast cells showed greatest decrease, the next decrease was in the left lung, trachea, buccal mucosa (cheek) and tongue by order in each group. 5) In the 48 hour bilateral nostril closure group, the mast cell showed greatest change followed by 5 hour bilateral nostril closure, 48 hour left nostril closure and 5 hour left nostril closure showed most slight change. This means the change of the mast cell in the bilateral closure group was more remarkable than the unilateral closure group, and the change of tissue mast cell of 48 hour closure group was remarkable than 5 hour closure group. 6) Morphologically, when the appearance of tissue mast cells decreased after various nostril closure with various intervals, the number of normal form decreased and the degranulation form, however, increased. Thereafter, as the appearance of mast cells increased, the number of normal form increased and degranulation form decreased. In general, the recovery of the number of normal and degranulation form somewhat delayed in time, in spite of the appearance of mast cells became normal range.