A number of attempts to prepare sulphanilylthiourea are described. The synthesis was accomplished by reacting acetylsulphanilylcyanamide with hydrogen sulphide under pressure and at elevated temperatures to form acetylsulphanilylthiourea, which was deacetylated to sulphanilylthiourea. This compound was also prepared directly from sulphanilylcyanamide and ammonium sulphide in a sealed tube. Acetylsulphaguanidine was prepared in an analogous manner by replacing the hydrogen sulphide with ammonium chloride. The conversion of acetylsulphanilylthiourea to sulphathiazole is described.