Type 1 diabetes mellitus (DM) is a result of inflammation and destruction of α-cells in the pancreatic islet cells. The aim of this study is to evaluate the associations of diabetes with soluble L-selectin (sL-selectin) and tumour necrosis factor-α (TNF-α) in children with type 1 DM; and also to evaluate the associations of these parameters with the disease period, glycaemic control state and puberty stage. Serum sL-selectin and TNF-α levels were measured in 44 children with type 1 DM and 44 healthy children. Neither the patients nor the control group showed significant difference between the levels of sL-selectin and TNF-α (sequence mean 12.17±1.62 ng/ml vs. 12.62±1.56 ng/ml and 7.27±3.1 pg/ml vs. 7.88±2.7 pg/ml). There was no statistically significant difference between children with duration of diabetes longer than 5 years and children with duration of diabetes shorter than 1 year. There was also no statistically significant difference between poor glycaemic control and good-acceptable glycaemic control patients. The present results indicate that sL-selectin and TNF-α serum levels are not increased and cannot be used as prognostic predictors in type 1 DM; and also sL-selectin and TNF-α do not change with the disease period, glycaemic control state and puberty stage.