Background: We evaluated the utility of the Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS) in predicting risk of gastrostomy tube (G-tube) insertion in patients with ALS. Methods: We conducted a retrospective study using the Pooled Resource Open-Access ALS Clinical Trials Database. People with ALS, at least two ALSFRS scores, and baseline swallowing subscore >1 were included. G-tube outcome was defined as reaching a swallowing subscore ≤1. Predictors were ALSFRS bulbar subscores (swallowing, speech, salivation). Survival analyses estimated median time to outcome and cumulative probability of outcome within 91 days. Individuals were censored at last ALSFRS score. Results: We included 6,943 participants. Median [95% CI] time to G-tube insertion was 245 [228, 285], 562 [547, 621], and 1,268 [980, 1,926] for baseline swallowing subscores of 2, 3, and 4, respectively. Probability of G-tube insertion was associated with baseline swallowing, speech, and salivation subscores (log-rank test p < 0.0001). For patients who transitioned to a swallowing subscore of 2 or 3, 18.1% [95% CI 16.1, 20.3] and 1.9% [95% CI 1.3, 2.7] required G-tube insertion within 91 days of score transition. Conclusions: ALSFRS bulbar subscores may identify patients at risk of G-tube insertion. Probability of G-tube insertion within 91 days is low if swallowing subscore ≥3.