A five year experience with bone marrow aspirates and biopsies positive for metastatic carcinoma is reviewed. Marrow examination in 25 cases detected metastasis. The common primary tumors with marrow metastasis were neuroblastoma, carcinoma breast and prostate. In 56% cases primary site could not be ascertained from bone marrow as metastatic tumor showed undifferentiated morphology. The study demonstrates the usefulness of combining trephine biopsy with aspirate examination for increased detection of bone marrow metastasis.