Despite the paucity of published literature on elasmobranch hematology and biochemistry, great interspecific diversity has been observed. Blood samples from 43 undulate rays (Raja undulata) (23 males, 20 females) hatched and raised at Oceanogràfic Aquarium, were analyzed for hematology and plasma biochemistry. Animals were divided into two age groups: 1 yr old (28 skates) and 2 yr old (15 skates). All individuals were clinically healthy on physical examination. Weight, total length, standard length, and disc width were recorded. No statistically significant differences were observed between male and female juvenile skates for the evaluated morphometric, hematologic, and plasma biochemical values. Once reference intervals (RI) were determined, blood samples from seven healthy adult skates housed at the same aquarium were collected for comparison. Statistically significant differences were observed in cholesterol, triglycerides, alkaline phosphatase, blood urea nitrogen, chloride, and sodium between juvenile and adult skates. This is the first article describing hematological and plasma biochemical RI for this species, increasing the clinical knowledge on elasmobranch blood analytics. These data will serve as a valuable diagnostic and research tool for professionals working with undulate rays and closer relatives in aquariums and in the field. Further studies using larger elasmobranch sample sizes are needed to determine reliable species-specific baseline health values and to evaluate the effect of intrinsic and extrinsic parameters on blood analytics more accurately.