Objective: To perform an economical evaluation of darunavir + low-dose ritonavir (DR) vs other protease inhibitors (PIs) in treatment-experienced HIV-1-infected patients in the Russian health care system. Methods: The modeled study was performed. A proportion of patients receiving alternative PIs, dosing regimen, and efficacy of drugs were extracted from multicenter randomized studies POWER 1 and 2 (Lancet 2007; 369:1169-78). The effect was measured in proportion of patients with viral load reduction of 1 log10 copies/ml or greater from baseline and with viral load less than 50 copies/ml. Other PIs in POWER studies were lopinavir + ritonavir, saquinavir, amprenavir, atazanavir, indinavir, nelfinavir; all patients in both groups received optimized background regimen. Cost of treatment with PIs for 48 weeks and cost-effectiveness ratio (CER) were calculated from the Russian reimbursement system point of view. Results: According to POWER studies, DR was much more effective than other PIs (61 vs 15 % of patients had viral load reduction =1 log10 copies/ml and 45 vs 10% achieved viral load <50 copies/ml), while cost of treatment was a little more for DR than other PIs (370,786.08 vs. 330,747.59 rubles or 15,105.64 vs USD 13,474.47). Incremental CER was 87,000 rubles (USD 3,544.34) for one patient with viral load reduction =1 log10 copies/ml and 114,400 rubles (USD 4,660.60) for one patient with viral load <50 copies/ml that seems reasonable for expensive antiHIV treatment. Conclusion: According to the model, DR seems to be much more effective than other PIs with affordable CER incremental ratio. Evaluation of DR treatment effectiveness and safety in common practice is needed.