The aims of this study were to examine the relationships between serum lipoprotein levels, glycaemic control and physical fitness in female Type I diabetic patients. Twenty-one patients were investigated. Those with the best glycemic control, as assessed by measurements of haemoglobin A1 levels, were found to have lower total triglyceride and VLDL triglyceride concentrations. They also had higher HDL and HDL2 cholesterol level than patients with less good control. Patients with high maximal oxygen uptake had higher HDL2 and lower LDL cholesterol levels as well as lower total triglyceride levels. It is concluded that both high aerobic capacity and good glycaemic control may be favourable for lipid status in Type I diabetic patients.