Aplant tissue based biosensor was proposed for voltammetric determination of epinephrine (EP) in pharmaceutical samples. The tissue homogenate was immobilized by crosslinking with glutaraldehyde on the glassy carbon. The polyphenol oxidase enzymes present in fibers of a myrtle tree fruits maintained high bioactivity on this biomaterial, catalyzing the oxidation of epinephrine to epinephrinequinone. Under optimize working conditions, the biosensor showed a linear response in the range of 10–100 μM. The limit of detection (LOD) was calculated as 3.2 × 10−6 mol L-1 (3.2 μM) (3σper slope). The reproducibility, expressed as the relative standard deviation (RSD) for seven consecutive determinations of 5.0 × 10-5 mol L-1 EP was 4.6%. The biosensor retained 70% activity after 11 days of storage in a phosphate buffer at 4°C. The applicability of this biosensor was demonstrated with the analysis of real samples and a good correlation was obtained between results acquired by the biosensor and those measured by spectrophotometric method. Such favorable results obtained with the myrtle tissue homogenate based biosensor, joined with the simplicity and low-cost of its preparation turns these procedures very attractive for EP quantification in pharmaceutical products.