Reference serum biochemical values were determined in blood samples from 15 male, 18 female, and 4 unsexed emus (Dromaius novaehollandiae) 1 to 48 months old. Serum biochemical values also were obtained for 19 male, 26 female, and 4 unsexed ostriches (Struthio camelus) 1 to 60 months old. Parametric (mean +/- 2 SD) and non-parametric (fifth to 95th percentile) reference ranges and linear trends as influenced by age were determined for enzyme activities and concentrations of glucose, inorganic phosphate, BUN, uric acid, creatinine, triglyceride, cholesterol, total protein, and albumin. Species differences for all analytes, except cholesterol and inorganic phosphate concentrations, were detected. Creatine kinase values in ostriches were higher than those in emus. There were no linear relationships between age and analyte values in emus, and sex did not significantly (P < 0.05) affect the values in emus. Analyte values in ostriches tended to increase with age, but cholesterol, creatine kinase, inorganic phosphate, and alkaline phosphatase concentrations decreased with age. Glucose, triglyceride, gamma-glutamyltransferase, and cholinesterase concentrations in ostriches were not linearly associated with age. Age had a greater effect on the analyte values of female ostriches than it did on male ostriches. Concentrations generally increased with age in female ostriches, except for cholesterol, cholinesterase, inorganic phosphate, and alkaline phosphatase concentrations, which decreased with age.