Lysyl oxidase plays a critical role in the formation of the extracellular matrix and its activity is required for the normal maturation and cross-linking of collagen and elastin. An 18 kDa propeptide (LOPP) is generated from 50 kDa pro-lysyl oxidase by extracellular proteolytic cleavage during the biosynthesis of active 30 kDa lysyl oxidase enzyme. The fate and the functions of the LOPP are largely unknown, though intact LOPP was previously observed in osteoblast cultures. Here we investigated the spatial localization of molecular forms of lysyl oxidase including LOPP in proliferating and differentiating osteoblasts by confocal immunofluorescence microscopy and by Western blots of cytoplasmic and nuclear extracts. In the present study, a stage-dependent intracellular distribution of LOPP in the osteoblastic cell was observed. In proliferating osteoblasts, LOPP epitopes were principally associated with the Golgi and endoplasmic reticulum, and mature lysyl oxidase epitopes were found in the principally in the nucleus and perinuclear region. In differentiating cells, LOPP and mature lysyl oxidase immunostaining showed clear co-localization with the microtubule network. The subcellular distribution of LOPP and its temporal and physical association with microtubules were confirmed by Western blot and far Western blot studies. We also report that N-glycosylated and non-glycosylated LOPP are present in MC3T3-E1 cell cultures. We conclude that LOPP has a stage-dependent intracellular distribution in osteoblastic cells. Future studies will investigate whether the LOPP associations with microtubules or the osteoblast nucleus have functional effects for osteoblast differentiation and bone formation.