PURPOSE We sought to evaluate the independent and interactive associations of planned treatment duration, celecoxib use, physical activity, body mass index (BMI), diabetes mellitus, and vitamin B6 with oxaliplatin-induced peripheral neuropathy (OIPN) among patients with stage III colon cancer enrolled in a clinical trial. METHODS We conducted a prospective, observational study of 2,450 patients with stage III colon cancer enrolled in the CALGB/SWOG 80702 trial, randomly assigned to 6 versus 12 cycles of adjuvant fluorouracil, leucovorin, and oxaliplatin chemotherapy with or without 3 years of celecoxib. OIPN was reported using the Common Terminology Criteria for Adverse Events (CTCAE) during and following completion of chemotherapy and the FACT/GOG-NTX-13 15-17 months after random assignment. Multivariate analyses were adjusted for baseline sociodemographic and clinical factors. RESULTS Patients assigned to 12 treatment cycles, relative to 6, were significantly more likely to experience higher-grade CTCAE- and FACT/GOG-NTX-13-reported neuropathy and longer times to resolution, while neither celecoxib nor vitamin B6 intake attenuated OIPN. Exercising ≥ 9 MET-hours per week after treatment relative to < 9 was associated with improvements in FACT/GOG-NTX-13-reported OIPN (adjusted difference in means, 1.47; 95% CI, 0.49 to 2.45; P = .003). Compared with patients with baseline BMIs < 25, those with BMIs ≥ 25 were at significantly greater risk of developing higher-grade CTCAE-reported OIPN during (adjusted odds ratio, 1.18; 95% CI, 1.00 to 1.40; P = .05) and following completion (adjusted odds ratio, 1.23; 95% CI, 1.01 to 1.50; P = .04) of oxaliplatin treatment. Patients with diabetes were significantly more likely to experience worse FACT/GOG-NTX-13-reported neuropathy relative to those without (adjusted difference in means, –2.0; 95% CI, –3.3 to –0.73; P = .002). There were no significant interactions between oxaliplatin treatment duration and any of these potentially modifiable exposures. CONCLUSION Lower physical activity, higher BMI, diabetes, and longer planned treatment duration, but not celecoxib use or vitamin B6 intake, may be associated with significantly increased OIPN severity.