Background: The optimal sequencing of brachytherapy and external radiotherapy (EBRT) for patients receiving combined therapy for localized prostate cancer has not been established, and in this series we report our experience of patients treated with brachytherapy followed by EBRT. Methods: Retrospective review of patients treated with combined Pd-103 brachytherapy and EBRT with minimum of 2 years of follow-up. Variables assessed included T stage, Gleason score, pre-treatment PSA, use of androgen suppression (ADT), EBRT dose and brachytherapy dose. Biochemical failure was defined as a PSA rise of ≥ 2 ng/mL above nadir. Results: 87 patients received Pd-103 brachytherapy (median 80 Gy) followed by EBRT (median 45 Gy). Median age was 65 years (49-80). By risk groupings (Zelefsky) 26.4% of patients were low risk, 47.1% were intermediate risk, and 26.4% were high risk. Most low risk patients had either perineural invasion or ≥ 50% involved biopsy cores. Neoadjuvant and concurrent ADT was given in 21% of patients. With a median follow-up of 56 months (range 24 to 113), there were 4 failures (all in the intermediate or high risk group), with an overall 5-year biochemical failure free survival (BFFS) of 91.8%. 2 patients had documented distant failures, while none of the presumed local failures had a positive biopsy. There was no statistical difference in BFFS based on risk group, T stage, Gleason score, initial PSA, or ADT use. The median PSA nadir was 0.1 and occurred at a median of 30 months from brachytherapy. A nadir of ≤ 0.5 was seen in 87% of patients and was associated with improved 5-year BFFS (100% vs 22%, p<.0001). The median time to PSA nadir for patients < 60 years was 34.5 months compared to 26.5 months in patients ≥ 60 (p=.036). Overall, treatment was well-tolerated with no cases of late Grade ≥ 2 rectal or urinary toxicity reported. Conclusions: Excellent long-term disease control and low morbidity was observed for patients with localized prostate adenocarcinoma treated with interstitial brachytherapy followed by EBRT. Future prospective research assessing the relative therapeutic ratio of alternate sequencing approaches would appear warranted.