Introduction: Image-guided fine needle aspiration (FNA) of the musculoskeletal system is expensive to perform and repeat, so on-site evaluation of adequacy (OSEA) is increasingly used to ensure an optimal sample. Metastatic disease to the musculoskeletal system is not uncommon and often requires OSEA when sampled. At large academic centers, cytotechnologists have filled the increased demand for OSEA. However, the performance of cytotechnologists has not been compared with that of cytopathologists for OSEA in FNA of metastatic disease involving bone and soft tissue. Methods: We retrospectively analyzed 10 years of data in which both cytotechnologists and cytopathologists performed OSEA for 1,995 FNAs of bone and soft tissue sites in which metastatic malignancy was suspected or found. We calculated adequacy and accuracy statistics in conjunction with other variables including imaging modality, biopsy site, accompanying core biopsy, tissue type, final diagnosis, and number of smears. Results: A total of 1,995 aspirates of metastatic disease carcinoma, melanoma or lymphoma to bone or soft tissue had OSEA performed by cytotechnologists (681, 33.7%) or cytopathologists (1,314, 66.3%). The adequacy downgrade rate was statistically equivalent (4.1 vs. 3.6%; p = 0.64). Conclusion: Cytotechnologists and cytopathologists perform with reasonable equivalence at OSEA of aspirates from metastatic carcinoma, melanoma or lymphoma involving bone or soft tissue.