Introduction: Asthma is a syndrome characterized by air flow obstruction that varies markedly spontaneously and with treatment, adding singulair treatment to handle symptoms in mild to moderate asthma may help improving symptoms in some patients. Patients & method: Singulair was prescribed for 4 weeks to treat 30 adult patients, aged 15-60 years with mild to moderate persistent asthma Results: After 4 weeks of singulair treatment good results were obtained with much improvement of nocturnal wakening, early morning wakening and exercise tolerance as well as PFT. Conclusion:The drug is effective and well tolerated by asthmatic patients.