Abstract Context Changes in telomere length (TL) have been linked to certain diseases. Studies on the effect of cortisol on TL have not led to conclusive results. Objective To determine whether TL is affected in pediatric patients with Cushing disease (CD) through an exploratory study. Design We studied 10 pediatric patients [mean age: 13.3 (2.6) years, 7 females], diagnosed and treated successfully for CD. TL was measured before and approximately 1 year after treatment. TL was compared with controls adjusting for age, and associations with disease characteristics were assessed. Results Adjusting for age, total lymphocyte TL of patients did not differ from controls during active disease (P = 0.13) but was shorter than controls at follow-up (P = 0.031). Total lymphocyte TL during active CD and at follow-up did not correlate with markers of hypercortisolemia. There was strong inverse correlation between TL during active disease and at follow-up with triglyceride levels at active disease (adjusted [Adj] R2 = 0.64; P = 0.02 and Adj R2 = 0.5; P = 0.036, respectively), suggesting that the higher the triglycerides, the shorter the TL in patients with CD. The change of TL between active disease and follow-up was positively correlated with systolic blood pressure (Adj R2 = 0.76; P = 0.006). Conclusions In this pilot study, TL is shorter in children with hypercortisolemia, a difference that becomes detectable only after cure of CD. Triglycerides and blood pressure appear to be factors that are associated with TL in these patients. Further studies are required to confirm these results.