<h3>Objective:</h3> To identify the predictors of time-to-second attack in patients with MOGAD. <h3>Background:</h3> MOGAD is a demyelinating disorder which can cause optic neuritis, transverse myelitis or acute disseminated encephalomyelitis. It can be monophasic or relapsing. Predictors of time-to-second attack in patients with an index demyelinating event are unknown in MOGAD. <h3>Design/Methods:</h3> Patients with a definite diagnosis of MOGAD, who tested positive for MOG-IgG and who are followed at Massachusetts General Hospital and Brigham and Women’s Hospital were included. Data on key clinical and demographic features including sex, age, race, treatment at onset, time-to-second attack and time to third attack were collected. A time-to-event survival analysis was performed using a Cox proportional hazards model. Univariate and multivariate regression analysis was performed. <h3>Results:</h3> We included 84 patients who had a definite diagnosis of MOGAD. The average age at first attack was 30 (IQR 17.0–46.5), and 62% of patients (n=52) were female. Median follow-up was 5.04 years (IQR 2.65–10.40). In total, 61% (n=51) of patients had a second attack, of which, 68% (n=35) experienced a third attack. After the first attack, 52% (n=42) patients were started on maintenance treatment. First available MOG titer was less than 1:100 in 29% of patients (n=25), and 1:00 or greater in 71% (n=51) of patients. Treatment status after the first attack significantly predicted longer time-to-second attack (HR = 0.46, 95% CI 0.23–0.92, p=0.028). Higher MOG titer did not predict time-to-second attack (HR=0.90, 95% CI 0.51–1.59, p=0.71). When adjusting for other covariates, MOG titers were not significantly associated with time-to-second attack. <h3>Conclusions:</h3> Early treatment after an index demyelinating event in MOGAD predicts a longer time-to-relapse, while MOG-IgG titer does not affect time-to-second attack. <b>Disclosure:</b> The institution of Dr. Molazadeh has received research support from Genentech, Inc.. Dr. Bilodeau has nothing to disclose. Ms. Salky has nothing to disclose. The institution of Dr. Bose has received research support from Multiple Sclerosis Society of Canada. Dr. Chitnis has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Novartis. Dr. Chitnis has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Roche-Genentech. Dr. Chitnis has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Academic CME. The institution of Dr. Chitnis has received research support from Novartis. The institution of Dr. Chitnis has received research support from Sanofi. The institution of Dr. Chitnis has received research support from Octave. Dr. Levy has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Mitsubishi Pharma. Dr. Levy has received personal compensation in the range of $500-$4,999 for serving as a Consultant for UCB Pharma. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Sanofi. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Horizon. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Levy has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Elsevier. Dr. Levy has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Various law firms. The institution of Dr. Levy has received research support from National Institutes Health.