Abstract Introduction. Due to the significant morbidity and mortality associated with bone metastasis in disseminated neuroblastoma (stage 4), efforts have been made to uncover potential markers and therapeutic targets to correctly diagnose, monitor, and treat this disease process. As described in the adult cancer literature, we propose that parathyroid-related peptide (PTHrP) is expressed in neuroblastoma cell lines and tissue and may be a key effector in the development and propagation of bone metastasis within this disease. Methods. Seven neuroblastoma cell lines were cultured and grown to confluency. In addition, 16 neuroblastoma tissue samples representing Stages I--IV, Ivs, and two bone marrow samples from a ganglioneuroma patient and a stage 4 neuroblastoma patient (with bone marrow involvement) were obtained under Institutional Review Board approval. RNA was then extracted from each of the cell lines and patient samples and reverse transcribed (RT). Conventional RT-PCR and real-time quantitative PCR were used to screen PTHrP expression in the cell lines, tissue, and bone marrow samples. Anti-PTHrP antibody was used to immunoblot neuroblastoma cell lysate for PTHrP. Results. Of the 7 cell lines tested, 6 of the neuroblastoma cell lines had detectable expression of PTHrP. These cell lines also displayed a positive 10-kDa band correlating with PTHrP on immunoblot of whole cell lysate. PTHrP transcript levels were found in all samples tested with the highest average levels found in stage 4 tissue samples. In addition the bone marrow sample from the ganglioneuroma patient had no detectable PTHrP level; whereas the bone marrow from the stage 4 patient showed an 18-fold expression above control (normal adult bone marrow). Conclusions. Because of the close association with osteoclastic stimulation and resultant bone resorption, PTHrP has proven to be an important marker and potential therapeutic target in many adult cancers. The results of this study indicate that innate PTHrP is present at the transcriptional and/or translational levels in most neuroblastoma cell lines and tissue samples. In addition, the presence of PTHrP over-expression in bone marrow positive neuroblastoma suggests that PTHrP plays a role in metastatic disease. Further study will reveal PTHrP function in bone metastasis.