A prospective study was performed of all children started on the ketogenic diet at our institution for intractable epilepsy from January 2003 to March 2007 (n = 137), examining for baseline and follow-up total cholesterol and triglyceride levels. Interventions for dyslipidemia were analyzed for their effectiveness. At baseline, 25% of children had hypercholesterolemia (>200 mg/dL), which increased to 60% for those receiving the ketogenic diet. Children receiving a solely formula-based ketogenic diet were less likely to have hypercholesterolemia than those eating solid food after adjusting for age and initial ketogenic ratio (P < .001). Only a slightly higher likelihood of a 20% decrease in cholesterol occurred for those children in whom a dietary intervention was made compared with observation alone (60% vs 41%; P = .11). Hypercholesterolemia occurs in most children receiving a solid food based ketogenic diet but improved in approximately half, even without interventions.