This retrospective study investigated the clinical efficacy and safety of bortezomib retreatment in patients with relapsed or refractory multiple myeloma (MM). A total of 30 patients who relapsed or progressed after ≥6 months since the last dose of their previous bortezomib therapy were included in this study. During the median 6 cycles (range: 2-12) of bortezomib retreatment, 10 (33.3%), 2 (6.7%), and 6 (20.0%) patients achieved complete response, very good partial response, and partial response, respectively. Grade 3 or 4 neutropenia (47.0%), thrombocytopenia (43.0%), anemia (10.0%), and peripheral sensory neuropathy (3.0%) were observed. The median time to progression, progression-free survival, and overall survival were 5.8 months (95% CI: 2.6-9.0), 5.5 months (95% CI: 4.2-6.8), and 13.4 months (95% CI: 6.1-20.7), respectively. Patients who received bortezomib retreatment ≥12 months from initial last therapy had a 1-year OS rate of 65.8% (95% CI: 43.5-88.1) while patients receiving retreatment after 6-12 months interval had a 1-year OS rate of 41.7% (95% CI: 13.9-69.5) (P = 0.038). In conclusion, this study demonstrates that retreatment with bortezomib is an effective strategy for patients with MM who relapsed at a long interval after initial bortezomib therapy.