The present work was devoted to investigation of the yield of levan and the molecular weight of the product from the marine Bacillus licheniformis FRI MY-55, on various temperatures and contents of sucrose. The isolate produced a varying amount of levan under various conditions. The result of the effect of various temperatures, ranging from 18 to 55 oC, on the production of levan by the B. licheniformis FRI MY-55 showed that the production of levan in B. licheniformis FRI MY-55 grown in medium supplemented with 20% sucrose at 23 and 30 oC progressively increased with increasing cultivation time and consequently reached the high level of 66.84 and 62.81 mg/mL (36 h), respectively, of culture broth after 36 hr of cultivation but began to decrease afterwards. The effect of temperature on molecular weight of levan indicated that the product distribution was affected by the fermentation time. After 5 hrs, the low molecular mass product (smaller than 5.67 KDa) predominated. However, as the fermentation proceeded further, the amount of high molecular weight product increased at 18-45oC . The higher molecular weight was reached at 13.45 KDa (18 oC, 72 h), 12.79 KDa (23 oC, 36 h), and 11.99 KDa (30 oC, 24 h), respectively. Our experiments show that the amount of synthesized levan increases proportionally with the increasing sucrose concentration in the medium in the range of 5 to 50%. The mass levan productivity (145.94 mg/mL) was obtained on the medium containing 50% of sucrose at 96 hr of incubation (40oC). Moreover, the time needed for levan formation increased with initial sucrose concentration. The effect of sucrose concentration on molecular weight indicated that the molecular weight of levan decreased with increased sucrose concentration up to 50% with a range from 11.46 KDa to 3.39 KDa. Combination of yeast extract and peptone in the culture medium led to maximal production of levan.