The effects of a new crystallization form A famotidine ( F_A ) on experimental gastric ulcers in rats, and compared the antiulcer effects of F_A with those of the form B of famotidine(F_B)were investigated . F_B has been used in clinic.The results showed that the anti-ulcer effects of F_A were as same as F_B and both of F_A and F_B were dose- dependent manner.