Treatment options for patients with metastatic pheochromocytoma/paraganglioma (PCC/PGL) are limited and none are curative. Very little is known about predictors of response to systemic treatment options. Our objective was to identify predictors of response to 131I-MIBG therapy. We performed a retrospective review of 71 consecutive patients with metastatic PCC/PGL seen in a single center between January 2000 and August 2016. Fifty-five patients had 123I-MIBG scans and 45 were positive. Interestingly, there was no difference in MIBG avidity based on primary tumor location (p=0.175) or between patients with SDHx mutation (N=28; 26 SDHB, 1 SDHD, 1 SDHA) compared to those without SDHx mutation (N=22; 1 NF1, 21 with no mutation identified) (p=0.732). Of the 45 patients with avid disease, 51% were female (n=23) and 84% (n=38) were treated with 131I-MIBG. The mean age at treatment was 50.9 years. The mean time from initial diagnosis of PCC/PGL to metastatic disease was 5.8 years (range 0-24.5) and did not differ between those with SDHx mutation (n=20; 19 SDHB, 1 SDHD) and those without (n=12; 1 NF1, 11 with no mutation identified) (5.3 vs 6.3 years; p=0.683). The median clinical progression-free survival (PFS) was 34.8 months (95%CI 12.3-58.3). There was no difference in clinical PFS based on SDHx mutation status, primary tumor location or high vs low dose treatment (p=0.589, p=0.211, p=0.463, respectively). Limitations of this retrospective study include small sample size and lack of formal RECIST criteria. Nevertheless, these data are interesting as the results demonstrate no clinical predictors of response to MIBG therapy and do not support the notion that SDHB mutations carriers with metastatic PCC/PGL are less likely to be MIBG avid and have a decreased response to MIBG therapy. In summary, these data suggest that all patients with MIBG avid metastatic PCC/PGL may benefit from MIBG therapy.