Increase of effectiveness of treatment for severe overactive bladder (OAB) symptoms in patients 40–65 and 66–80 years of aged with combined antimuscarinic drugs. This placebo‐controlled longitudinal study was performed on the basis of Regional Diagnostic Centre (Vladivostok city, Russian Federation) from 1 June 2011 to 30 December 2012. Assignment of patients (n = 299, average age: 67·1; women: 174 or 58·2%, men: 125 or 41·8%) was random blind. All patients were distributed into two age groups 40–65 and 66–80 years, and then into groups in accordance with treatment algorithm. Group A1 – patients below 65 years old treated with Trospium 60 mg/day + Soilfenacin 20 mg/day, Group A2 (n = 51; also below 65 years old): Trospium 30 mg/day + Soilfenacin 10 mg/day, Group A3 (n = 45, below 65 years old): Placebo. Group B1(n = 52; over 65 years old): Trospium 60 mg/day + Soilfenacin 20 mg/day, Group B2 (n = 54; over 65 years old): Trospium 30 mg/day + Soilfenacin 10 mg/day, Group B3 (n = 49, over 65 years old): Placebo. Period of treatment in all groups was 2 months. All patients underwent urodynamic examination at the beginning and at the end of the study. International Consultation on Incontinence Questionnaire‐Short Form (ICIQ‐SF) questionnaires and bladder diaries were used for evaluating clinical effectiveness of treatment and patients' satisfaction. Frequency of episodes of incontinence (EI) per day was taken as basis for clinical evaluation of treatment effectiveness. Value EI >3/day was considered as severe dysfunction of lower urinary tract (LUT). Patients below 65 years of age treated with double‐dosed antimuscarinics showed the best results both for improvement of main urodynamic and clinical parameters and for number of persons completely or partially satisfied with effect of the treatment (81·2/12·5%). In the group of patients over 65 years of age treated with standard‐dosed Trospium and Solifenacin 74·5/17·6% of patients were completely or partially satisfied with effect of the treatment and experienced significant improvement of main clinical and urodynamic indexes. Comparison of pattern of urodynamic indices, decrease of frequency of EI, correlation of Bladder capacity let us suppose that effectiveness of treatment algorithms is similar in all groups. All urodynamic and clinical indices in the group of patients over 65 years of age, who were treated with double‐dosed antimuscarinics, were significantly different from initial data, and majority of patients were completely or partially satisfied (76·9/5·8%) with results of the treatment. Clinical observation indexes, including EI, and urodynamic examination of the group of elderly patients, who were treated with standard‐dosed Trospium and Solifenacin, showed absence of significant result, and number of patients satisfied with the treatment was minimal. For effective management of overactive bladder with severe symptoms in 40 to 65‐year‐old patients prescription of two standard‐dosed antimuscarinic drugs, preferentially with different spectrum, is suf...