OBJECTIVE To investigate whether fasting during Ramadan influences injury incidence in professional Muslim and non-Muslim footballers. METHODS Prospective cohort study. METHODS Professional First Division League of Qatar. METHODS About 527 male football players (462 Muslim and 65 non-Muslim) from 7 league clubs (first year of data collection) and 8 clubs (second and third years). METHODS Daily collection of training and match exposure from August 2008 until April 2011 by club medical staff. Injuries during training and match play were recorded on standardized injury cards. METHODS Injury incidence was calculated as number of injuries per hour exposed to risk, and expressed as rate per 1000 hours. The probability of injury for different Arabic months between Muslims and non-Muslims was calculated using Generalized Estimating Equations (GEEs). RESULTS There was no significant difference in total, match, and training injury incidence between the Ramadan and non-Ramadan periods. Non-Muslim footballers had a significantly higher injury incidence rate than Muslim footballers both during Ramadan (8.5 vs 4.0 injuries/1000 hours, P = 0.009) and non Ramadan (6.6 vs 4.9 injuries/1000 hours, P = 0.004) periods. The GEE analysis revealed that after adjusting for age and random factors (month and club), the probability of match injury among non-Muslims was the highest in Ramadan and the 2 consecutive following months (adjusted odds ratio of injury among non-Muslims compared with Muslims was 3.7 [95% confidence interval (CI), 1.7-7.9], P = 0.001 during Ramadan (ninth) month; 2.4 (95% CI, 1.1-4.9), P = 0.021 during 10th month; and 2.7 (95% CI, 1.2-5.8), P = 0.013 during 11th month). Finally, there was no change in injury patterns over the months of the Islamic calendar. CONCLUSIONS Ramadan does not impact injury incidence for Muslim footballers in Qatar, suggesting the current adjustments and scheduling of football activities during Ramadan are sufficient. The increased match injury among non-Muslims during and 2 months post-Ramadan may suggest less effective coping strategies.