Twelve clinical biochemical parameters were determined in 97 animals of all age groups and both sexes of the endangered Catalonian donkey breed. Significant sex differences were observed for phospholipid concentration (P<0·01). Evaluating the effect of management practices on the various parameters showed significant differences for total bilirubin (P<0·001) and creatinine (P<0·05) concentrations and γ-glutamyltransferase (P< 0·05) activity. Moreover, it was observed that inorganic phosphorus concentration decreased with age (P<0·001), whereas albumin and triglyceride concentrations increased with age (P<0·01 and P<0·001, respectively). Comparison of biochemical ranges obtained for the Catalonian donkey breed with reference ranges for other breeds and populations (Mammoth, USA donkeys, UK donkeys, Indian donkeys and Poitou donkeys), indicated that most values were similar, with the exceptions of enzymatic activities mainly. The results reported in the present study could serve as reference ranges for donkey populations.