Objectives: Prostate cancer is the second most common malignancy in the world next to lung cancer and it is the leading cause of morbidity and mortality among men. The most common metastatic site in prostate cancer is the bone. This study is aiming at finding the pattern and frequency of bone metastasis among prostate cancer patients at Ocean Road Cancer Institute, Tanzania.

Methods: This was a cross section retrospective hospital based descriptive study involving 139 patients with prostate cancer who were seen from June 2014 to June 2016 whose bone scan were reviewed.

Results: Bone metastases were found in 77 patients (55.4%) The prevalence was higher in the age group between 60 and 79 (56.3%) however there was no statistical significance between age and occurrence of bone metastasis. Patient who had high PSA level and Gleason score had more occurrence of skeletal metastasis.

Spine was the most common site for bone metastasis constituting 72 patients (51.8%) of all the patients followed by ribs metastasis (31.7%), Also it was shown that of the spine metastasis, lumbar spine was more frequent affected (48.2%) followed by thoracic and cervical spine (41.0% and 27.3% respectively)

Conclusion: The prevalence of skeletal metastasis in patients with Prostate cancer at Ocean Road Cancer Institute was high (55.4%). The prevalence was higher in patients with PSA level more than 20 and those with Gleason score of more than 7. Spine was the commonest site for metastasis and of the spine, metastasis lumbar spine metastasis was most frequent site.

Recommendations: It is recommended that bone scan should be done as baseline in patients with prostate cancer particularly those with PSA level more than 20ng/ml and Gleason score of more than seven.