Objectives: A mechanism of bone/titanium integration has not been understood. We postulate that cellular phenotypes other than osteoblastic one, are involved in the mechanism. Bone marrow-derived osteoblastic culture has been performed using culture-expanded osteoblastic cells to obtain a sufficient number of cells. However, chondroprogenitor cells dedifferentiate, and chondrogenic potential of the bone marrow stromal cell depresses during the expansion process, which may result in misinterpretation of in vivo phenomenon of osseointegration. The objective of this study is to examine chondroblastic phenotype possibly emerging or being altered during mineralized culture on titanium using the extracted whole bone marrow cells without culture-expansion. Methods: Bone marrow cells obtained from the femurs of 8-week male rats were directly seeded onto either the polystyrene culture dish, machined or acid-etched titanium disc. Total RNA samples were subjected to a RT-PCR assay for expression of osteoblastic and chondroblastic genes at days 3, 7, 14, 21 and 28. Morphologic and elemental analyses of the mineralized tissue were performed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. Cross sections of mineralized culture were also examined immunohistochmemically. Results: The expression of osteoblastic genes, such as collagen I, osteocalcin and osteopontin was upregulated on titanium cultures on day 21 and/or 28. Collagen II, IX, X, XII and aggrecan, which are chondroblast-specific genes, were also upregulated 2-6 fold on titanium at days 21 and 28. Collagen IX, X, XII and aggrecan were further upregulated in the acid-etched surface. EDS analysis revealed more sodium and sulfur elements on the titanium cultures compared to the polystyrene culture. Immunohistochemistry confirmed collagen II synthesis localized in the mineralized tissue on titanium. Conclusions: Titanium and its surface roughness promote not only osteoblastic but also chondroblastic phenotypes of whole bone marrow cells, which may provide new basis for understanding the mechanisum of tissue/titanium integration.