OBJECTIVES: To examine the association between types of chronic conditions combinations and initial cancer treatment among elderly Medicare Beneficiaries with localized prostate cancer.  METHODS: A population-based retrospective cohort study was conducted using the Surveillance, Epidemiology and End-Results (SEER)-Medicare linked database. The study cohort consisted of elderly men (> 66 years) with localized prostate cancer diagnosed between 2002 and 2009 (N = 98,264).  The initial cancer treatment received during the six months after cancer diagnosis consisted of: 1) Radical Prostatectomy (RP); 2) Radiation Therapy (RT); 3) Hormone therapy; and 4) No treatment. Pre-existing chronic conditions combinations were classified into eight groups: 1) only cardio-metabolic conditions(CM); 2) only mental health conditions(MH) ; 3) only respiratory conditions(RESP); (4) CM and MH; (5) CM and RESP; (6) MH and RESP; (7) all three-CM, MH and RESP; and 8) none of the three types of conditions.  RESULTS: Only 20% did not receive any cancer treatment; 47.4%, 22.1% and 10.5% received RT, RP, and 10.5% hormone therapy respectively. In multinomial logistic regression, elderly men with only RESP were more likely to receive RP as compared to those with all the three types of chronic conditions; those with only CM, only RESP, CM and MH or CM and RESP were more likely to receive RT.  No significant associations were observed between the receipt of hormone therapy and types of chronic conditions.   CONCLUSIONS: Despite the lack of evidence of the long-term benefits, elderly men with chronic conditions and localized prostate cancer received treatment for prostate cancer.