Background Biosimilars are used at the same dose as the reference product to treat the same disease and may offer cost savings in clinical practice. Epoetin zeta is an epoetin biosimilar that is licensed for use in Europe for the treatment of chemotherapy-induced anaemia. Purpose To evaluate the efficacy of epoetin zeta and to analyse the economic effect of biosimilar incorporation. Materials and methods Retrospective, observational study of epoetin zeta, administered subcutaneously, in patients with cancer who had anaemia and were undergoing chemotherapy in the Ribera Health Department. The patients had previously been treated with epoetin alfa or darbepoetin alfa. The number of patients who presented all these requirements was 28. The study comprised two periods: 12 months in treatment with epoetin alfa/darbepoetin and 12 months in treatment with epoetin zeta. Haemoglobin (Hb) concentration and dose of epoetin were compared. The doses were adjusted to obtain an optimal target level of 10–12 g/dL. To describe statistically significant changes, the two sided Student`s t-test was applied using paired observations. Results When comparing the mean Hb concentration for each patient in each of the periods of study treatment before and after switching to epoetin zeta, there were no statistically significant differences in 71% of patients (p > 0.05). It was observed that 46% of patients needed an increase in the dose of epoetin, during treatment with epoetin zeta to maintain the concentration of haemoglobin within the target level. The mean (±SD) Hb concentration during epoetin alfa treatment was 10.78 ± 1.73 g/dL and during epoetin zeta treatment was 11.06 ± 2.06 g/dL. Significant statistical differences in the comparison of two means were not observed (p = 0.49). The mean (±SD) Hb concentration during darbepoetin treatment was 9.87 ± 1.39 g/dL and during epoetin zeta treatment was 10.94 ± 1.71 g/dL. Significant statistical differences in the comparison of two means were observed (p = 0.01). No statistically significant differences were observed in the comparison of the Hb values within the optimal target level between epoetin alfa (or darbepoetin alfa) and epoetin zeta. Cost per patient was reduced from 1190 ± 571 €/month to 826 ± 394 €/month. This means a saving of 364 € per patient per month during the treatment with epoetin zeta, representing an annual saving of 4370€ per patient. Conclusions Despite the limited number of patients, it has been demonstrated that epoetin zeta was effective in the treatment of anaemia in patients with cancer receiving chemotherapy. In addition, epoetin zeta improved the efficiency of treatment, significantly reducing costs. No conflict of interest.