In the present study, we have decided to evaluate if serum transforming growth factor-beta 1 (TGF- β 1) concentrations may have diagnostic value in predicting the occurrence of diabetic retinopathy (DR) in juvenile patients with type 1 diabetes mellitus (T1DM). The study included 81 children and adolescents with T1DM and 19 control subjects. All study participants had biochemical parameters examined, underwent an eye examination, and 24-hour blood pressure monitoring. Moreover, serum concentrations of TGF- β 1 were measured. The group of patients with T1DM and nonproliferative diabetic retinopathy (NPDR) had statistically significant higher serum levels of TGF- β 1 (P = 0.001) as compared to T1DM patients without retinopathy as well as the healthy control subject. The threshold serum TGF- β 1 concentrations which had a discriminative ability to predict the presence of DR were calculated using the receiver operating characteristic (ROC) curves analysis and amounted to 443 pg/ml. The area under the ROC curve (AUCROC) was 0.80, and its population value was in the range of 0.66 to 0.94. The sensitivity and specificity were calculated to be 72% and 88%, respectively. Our results suggest that TGF- β 1 serum concentrations may be an additional parameter in predicting the occurrence of DR in juvenile patients with T1DM.