Obesity and osteoporosis may be linked as both adipocytes and osteoblasts originate from common mesenchymal stem cell precursors. Based on some studies, both conditions may benefit by increased n‐3 polyunsaturated fatty acid (PUFA) intake and decreased n‐6/n‐3 PUFA ratio. n‐3 fatty acids (alpha‐linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) are frequently taken as supplements but their efficacy in all aspects of bone metabolism has not been investigated. The purpose of this study is to investigate the effects of some frequently used oil supplements on the proliferation of mouse bone marrow stromal cells (ST2), pre‐adipocytes (MC3T3‐L1), and pre‐osteoblasts (MC3T3‐E1). Cell media containing oils was replaced every 2 days until day 8 when cell proliferation was measured. Fish oil significantly increased ST2 and MC3T3‐E1 cell proliferation, however, the lower dose had the greatest effect on MC3T3‐E1 cells. Flax oil also significantly increased MC3T3‐E1 cell proliferation but had no effect on ST2 cells. Neither fish nor flax oil had a significant effect on MC3T3‐L1 cell proliferation. This preliminary research suggests that various n‐3 PUFAs have different modes of action and fish (EPA and DHA) and flax (ALA) oil may benefit osteoblastogenesis. Further research in this novel area is required.