OBJECTIVES: We took into consideration clinical effectiveness, costs and macroeconomic consequences of supplementation with two slow release kalium compounds (Kalipoz prolongatum vs Kaldyum) from payer (public insurer and patient) perspective. METHODS: Results of a systematic review of clinical trials referring to hypokaliemia treatment were used to assess effects of kalium supplementation with Kalipoz or Kaldyum. DDD (Defined Daily Dose) costs for supplementation were calculated from payer perspective (based on retailed prices of the drugs); simulation was done to compare economic consequences per therapy for payer in case of Kaldyum replacement by Kalipoz; total annual sales of the drugs in Poland were taken into account to assess macroeconomic consequences of kalium supplementation. RESULTS: Clinical effects of the compared drugs are similar, adequate level of kalium in blood could be obtained with both of the drugs. DDD for potassium chloride compounds is 3 g; cost of daily supplementation for payer is 1.36 pln (0.3€) in case of Kalipoz and 2.24 pln (0.48€) or 2.5 pln (0.54€) for Kaldyum tablets (for 100 caps and 50 caps package respectively). Supplementation for a period of a week with high dose (3g) of Kalipoz is cheaper from payer perspective than with Kaldyum 100 caps and Kaldyum 50 caps (difference is 6.18 pln (1.34€) and 7.98 pln (1.73€) respectively). Taking into consideration macroeconomic consequences of potassium supplementation savings for payer when use Kalipoz in place of Kaldyum could be as high as 5.6 m pln (1.2€m) per year. CONCLUSIONS: Kalipoz prolongatum in place of Kaldyum supplementation significantly reduce treatment costs for payer in treatment of patients with hypokaliemia.