BACKGROUND Little is known about the baseline clinical pathology of the dugong (Dugong dugon), a vulnerable marine mammal found in tropical coastal marine systems. OBJECTIVE The purpose of the study was to collect and determine reference intervals (RI) for select serum biochemical variables for dugongs, and to analyze differences between males and females and different age groups. METHODS Reference intervals were established from 103 apparently healthy, wild-caught dugongs for 31 analytes using a Beckman Coulter AU400 Automated Chemistry Analyzer and an Olympus AU680 Chemistry-Immuno Analyzer. RESULTS Significant differences (P < .05) in some of the variables were found related to size class, sex, and pregnancy status. Adult dugongs had higher serum sodium, potassium, bicarbonate, glucose, and l-lactate concentrations and higher anion gap, compared to sub-adults. Male dugongs had higher triglyceride and l-lactate concentrations than females. Pregnant females displayed higher l-lactate levels compared to nonpregnant animals. Statistical differences in variables within the population contributed to better understanding of the physiologic differences between cohorts. Some serum biochemistry changes observed in this study here also potentially include some effects of pursuit on dugongs (eg, higher l-lactate); however, as all dugongs were subject to similar capture and handling, serum biochemistry RI should be considered as normal for captured dugongs. CONCLUSIONS The serum biochemical RI documented here are considered representative of a population of healthy captured dugongs. They provide a baseline for health surveillance of this and other dugong populations.