Adenocarcinoma with osteoblastic metastases is classically seen in prostate, breast, and lung primaries. Less common primary sites include thyroid, kidney, and stomach. We present two cases of primary gastrointestinal adenocarcinoma with metastatic osteoblastic activity from two previously unreported sites. The first case represents an esophageal adenocarcinoma arising in a background of intestinal metaplasia that metastasized with osteoblastic activity to the deltoid muscle. The second case demonstrates a Stage IV sigmoid colon adenocarcinoma with osteoblastic metastases to the liver and lymph nodes. The findings indicate that metastases from various gastrointestinal primary adenocarcinomas can have prominent bone formation.