Children with hyperlipidemia secondary to renal disease develop premature atherosclerosis and glomerulosclerosis. The aims of this pilot study were to find the dosage and short-term efficacy of simvastatin and potential adverse events in children with chronic kidney diseases. This was a random, double-blind, placebo-controlled, cross-over clinical trial performed on children with hyperlipidemia secondary to kidney disorders. After being placed on a diet for 3 months, patients were randomly placed in one of two balanced group blocks and treated with diet plus placebo or simvastatin at doses of 5 mg for children weighing 30 kg or less and 10 mg for children weighing over 30 kg, for 1 month, and then doubled for two more months. After this treatment, patients were placed on a diet for a 3-month washout period. During the last trial phase, patients previously treated with simvastatin were administered a placebo, and vice versa. A total of 25 patients with ages ranging from 4 years to 17 years were included in the study. A significant decrease in the levels of serum cholesterol (26.4%), low-density lipoprotein (LDL) (35.4%) and triglycerides (23.1%) was noted during the study, primarily during the simvastatin treatments, in which case cholesterol, LDL and triglycerides decreased by 23.3%, 33.7% and 21%, respectively. High-density lipoprotein (HDL) levels increased moderately (10.7%) during the study but without differences during simvastatin treatment. No differences were found across groups with respect to adverse events. In the short-term the combination of diet and simvastatin was effective in lowering hyperlipidemia in children with renal disorders.