Introduction: Chronic kidney disease (CKD) is characterized by slow, progressive, and irreversible loss of kidney function. CKD has become a serious public health issue because of its increasing morbidity and mortality rates. The present study aimed to investigate factors associated with hematomas caused by arteriovenous fistula (AVF) at a Renal Replacement Therapy Unit in the state of Rio Grande do Sul, southern Brazil. Methods: In this cross-sectional study, 72 patients with CKD aged 18 years or over, presenting with AVF, and undergoing three hemodialysis sessions per week were evaluated from June 2014 to March 2015. Prevalence ratios (PRs) with 95% confidence intervals (95% CIs) were estimated for identification of risk factors associated with AVF. P-values < 0.05 were considered significant. Results: Sex, age, self-reported skin color, educational level, hypertension, diabetes, nephrotic syndrome, congestive heart failure, and hepatitis C were not associated with hematoma formation (i.e., all estimated PRs had p-values > 0.05). The single factor associated with hematomas was AVF time shorter than 60 days (PR = 2.04; 95% CI: 1.28-3.27; p < 0.01). Conclusion: AVF maturation time was associated with higher prevalence of hematomas at the cannulation site. Therefore, AVF time should be given special attention in patients undergoing renal therapy at dialysis centers.