The internal anal sphincter (IAS) is an important struc ture which is resp onsible to maintain the resting tone . It is known to be responsible for occurrence of fissure in ano. Action of Mahanarayana oil on hypertonic sphincter was evaluated in this study. Three groups were formed with randomly selected forty five patients having symptoms of acute fissure in ano . There were fifteen patients in each group having the age between eighteen to seventy five years. Group I, the control group, was treated with Thriphala Guggulu , Hingvashtaka choorna , Powder Isab gol and sitz bath. Group II was treated with Ointment Diltiazem locally , with sam e regimen as in Gr oup - I. Group III was treated with local application of Mahanarayana oil, with same regimen in G roup - I. All the three groups were underwent ano rectal manometry procedure, before and after treatment by sixteen channel ano rectal manomet ry technique to evaluate resting pressure, squeeze pressure, volume of first sensation and Recto anal inhibitory reflex (RAIR) . It wa s observed that resting pressure (mmHg) within group, compared by pair t test was significantly decreased in Group III after treatment as compared to Group II and I (100.87 ± 30.981SD vs 75.13 ± 12.489SD (P 0.05). Similarly , squeeze pressure, and Volume of first sensation e tc. showed significant difference in Group I II . Hence it can be concluded that Maha narayan a oil local application caused a significant decline in the R esting anal pressure with other parameters and also fo und to be better to relieve the acute spasm of anal sphincter in acute fissure in ano.