A study of normal serum immunoglobulin-E (IgE) and immunoglobulin-G (IgG) antibody concentrations in Cynomolgus-monkeys was conducted. The purpose was to establish baseline values of IgG and IgE concentrations in the Cynomolgus-monkey sera using methods commonly utilized for determining these parameters in human sera. Sera from 44 adult male Cynomolgus-monkeys (Macaca-fascicularis) were analyzed for IgE using a radioimmunoassay technique and IgG using an immunochemistry analyzer. The mean and median IgE concentrations were 43.2 and 39.1 nanograms per milliliter (ng/ml), respectively. The mean and median IgG concentrations were 1563 and 1390 milligrams per deciliter (mg/dl), respectively. The 0 and 100 percentile IgE concentrations were 12.9 and 147.2ng/ml, respectively. The 0 and 100 percentile IgG concentrations were 930 and 2840mg/dl, respectively. The authors note that serum IgE and IgG concentrations in Cynomolgus-monkeys probably depend on the same factors that determine IgE and IgG concentrations in humans such as age, sex, heredity, allergy history, and recurrent or extant bacterial or parasitic infections. The measured IgE and IgG concentrations agree well with the range of values reported for humans and other monkey species.