Abstract: It was found in our previous work that p-carboxymethylmercaptobenzencstibonic acid(lb) was highly effective against schistosomiasis japonicum.In the present work p-carboxymethoxy- benzenestibonic acid(Ⅰc),a structure-related compound,was prepared for pharmacological examina- tion.Since p-carboxybenzenestibonic acid(Ⅰa)is also a valuable schistosomicide,its homologues, p-carboxymethyl(Ⅰd)and p-carboxyethyl(Ⅰe)as well as the hydrazide(Ⅰj)were therefore pre- pared.Moreover,the synthesis was extended to the stibonic acid derived from salicylic acid(Ⅲa). The stibonic acids were synthesized by means of the Scheller reaction,p-Carboxymethyl,p- carboxyethyl-,p-carboxymethoxy-and 4-carboxy-3-hydroxy-aniline were diazotized,and then treated with antimony trichloride.The double salts so formed were decomposed under the catalytic ac- tion of cuprous chloride and then hydrolyzed,giving the corresponding stibonic acids.The stibonic acids were purified through the formation of crystalline pyridinium double salts (Ⅱ,Ⅳ). The double salts were recrystallized by dissolving in dilute aqueous hydrochloric acid and then salting out on addition of concentrated hydrochloric acid.When the double salts were recrystal- lized in hot ethanolic hydrochloric acid,the carboxyls were esterified,and consequently the carbethoxy-substituted stibonic acids(Ⅰg,Ⅰh,Ⅰi,Ⅲb)were obtained.The hydrazide(Ⅰj)was prepared on treatment of p-carbomethoxybenzenestibonic acid with hydrazine hydrate.