Signet ring cell carcinoma is a poorly differentiated adenocarcinoma in which the tumour cells invade singly or in small groups. Early stages of the disease can be missed easily when using regular haematoxylin and eosin staining. This is a report of a case in which routine screening of gastric biopsies with the Genta stain was responsible for rapid identification of signet ring carcinoma. The patient, a 29 year old woman, had a large portion of the antrum excised surgically for signet ring cell gastric carcinoma. Follow up endoscopy six years later showed no evidence of tumour. Twenty six large cup biopsies were obtained and a single focus of signet ring tumour cells infiltrating the surface mucosa in single files was seen. The diagnosis was missed on haematoxylin and eosin stain by three senior pathologists but owing to the Alcian blue component of the Genta stain the tumour cells were recognised easily. Thus, the Genta stain not only facilitates detection of Helicobacter pylori but also allows for simultaneous visualisation of gastric morphology as well as signet ring carcinoma that can be missed with conventional stains.