Risk factors for cellulitis in lymphedema (LE) have never been evaluated in controlled studies. The objective of this study was to assess the risk factors for cellulitis in patients with LE using a case-controlled study method. Medical records of patients from November 2009 to September 2011 who met the following criteria were retrieved and analyzed: (a) clinical diagnosis of LE of the limb, (b) aged 18 or above, (c) no food allergy history and (d) no medical diagnosis of cancer metastasis. Overall, there were 179 cases of LE with cellulitis. Each case was matched by age (+/- 5 years) and gender with a patient with LE and without cellulitis for controls. Logistic regression with backward selection procedure was used to identify independent risk factors. The area under the receiver operating characteristics (ROC) curve of the final model was calculated. Independent risk factors for cellulitis in patients with LE were percentage difference in circumference of the limb (adjusted odds ratio (AOR)=1.07, 95% confidence interval (CI)=1.04-1.10), primary LE diagnosis (AOR=3.36, 95% CI=1.37-8.22), food-induced complication experiences (FIE: AOR=6.82, 95% CI=2.82-16.51) and systolic blood pressure (AOR=1.02, 95% CI=1.01-1.04). The area under the curve for the model was 0.80 (95% CI=0.75-0.85, p<0.001). No association was observed with hypertension, diabetes mellitus, body mass index and the duration of LE. This first case-controlled study highlights the important roles of dietary factors, percentage difference in circumference of the limb, and systolic blood pressure for developing cellulitis. The results suggest that controlling the percentage difference in circumference of the limb and systolic blood pressure together with restriction of fatty food and meat consumption may result in a decreased incidence of cellulitis among patients with LE.