Neurofibromatosis type 1 (NF1) and tuberous sclerosis (TSC) are autosomal dominant neurocutaneous diseases. Epilepsy, malignancy and other neurological complications are common in both diseases. We aimed to investigate the thiol/disulphide balance as an oxidative stress marker in children who suffer from NF1 and TSC. Twenty-two patients with NF1, 20 TCS, and 22 healthy control subjects were included in the study. The total thiol, native thiol, and disulphide levels were measured and the disulphide/native thiol, disulphide/total thiol and native thiol/total thiol ratios were calculated and compared in three groups. The mean age and sex distribution of the patients with TSC and NF1 and the healthy control were similar. The total thiol, native thiol, and disulfide level was lower in TSC and NF1 group than the healthy control group. There were no significant differences among disulphide/native thiol and disulphide/total thiol ratios of three groups. We detected that the total thiol, native thiol, and disulfide levels were lower in TSC and NF1 group than the healthy control group. These results indicate that dynamic thiol-disulphide homeostasis can be used as a marker of oxidative stress in clinical trials with TSC and NF1.