This paper presents the resulţs of Montelukast sodic therapy in 16 asthmatic patients, in a prospective study. Montelukast sodic was given in severe chronic asthma treated by inhaled or systemic steroids before. Patients were followed up for three months regarding: clinical symptoms, respiratory function (FEV), blood and sputum eozinophyls. Short term therapy showed a great improvement in day and night symptoms, a reduction of sputum and blood eozinophyls and an increased FEV. Long term therapy could be protective for asthma exacerbations and will provide constant good life quality of asthmatics.