Four cases of adenoacanthoma of the pancreas were collected and the literature reviewed. This uncommon histologic variant appears as aggressive and malignant as the more common adenocarcinomas. Two of these four cases had originally been diagnosed as squamous cell carcinomas and were shown to be adenoacanthoma in type after additional sections were examined microscopically. It is the authors' opinion that any squamous cell carcinoma of the pancreas must be thoroughly examined for adenocarcinomatous elements before it can be classified as being pure squamous in type. Also, because metastases may be predominantly of either squamous or adenomatous type, the presence of squamous carcinoma in a metastatic lesion does not eliminate the possibility of a pancreatic primary nor does the finding of two distinct histologic types of metastases necessarily imply two separate primary malignancies. The terminology and origin of this histologic type of pancreatic tumor are discussed.