This study assessed virological failure rates, HCV retreatment uptake, and outcomes across 33 primary and tertiary HCV care programs in the Australian REACH-C observational cohort (March 2016-June 2019).  Following initial treatment, 4.4% (n = 408) of individuals with known SVR12 outcome experienced virological failure (VF); early treatment discontinuation was reported in 28%.  Several factors including male gender, recent injection drug use, cirrhosis, and GT3 increased likelihood of VF.  Retreatment was initiated for 213 (52%) individuals: among those with VF identified in primary care, 46% were referred to tertiary care, and among those with VF identified in tertiary care, 8% were retreated in primary care.  Median time from identification of VF to retreatment decreased from 407 days (2016) to 152 days (2019).  Individuals without treatment discontinuation (n = 154) were most commonly retreated with SOF/VEL/VOX x 12 weeks (48%) whereas people with discontinuation (n = 59) were most commonly retreated with SOF/VEL x 12 weeks (34%) or GLE/PIB x 8 weeks (20%).  Per-protocol SVR12 for retreatment was 81% overall: rates were similar between primary care and tertiary care settings as well as by initial treatment discontinuation history.  33 individuals experienced second VF: cirrhosis increased likelihood of second VF while SOF/VEL/VOX retreatment decreased likelihood of second VF (retreatment setting and prescriber type were not associated with second VF).  Of 15 people retreated after second VF, SOF/VEL/VOX was the most commonly selected combination (73%) with subsequent per-protocol SVR12 of 90%.