We determined the blood biochemistry parameters for the breeding population of green turtles (Chelonia mydas) in the Aves Island Wildlife Refuge (Venezuela), the second largest breeding colony of relevance in the Caribbean. We collected 59 blood samples (48 nesting females and 11 adult males) by puncturing the dorsal cervical sinus. Sexual maturity was estimated by measuring curved carapace length, curved carapace width, and tail length (only in males). We used colorimetric techniques for biochemical analysis. Mineral concentrations in the samples were determined by atomic absorption (Ca, Mg, Zn, Cu, and Mg) and emission (Na and K) spectrometry. This study provides valuable biochemistry reference values for breeding populations of green turtles from Venezuela and the Caribbean. The population is considered healthy, with parameter values coinciding with previously reported reference ranges of species in the Caribbean and Atlantic populations. We conclude that, for the population in the Aves Island Wildlife Refuge, variability in the values obtained for total protein, albumin, blood urea nitrogen, alanine aminotransferase, glucose, triglycerides, HDL-cholesterol, calcium, phosphorus, magnesium, and copper was directly related to factors such as sex and animal size.