To evaluate the effects of optimal pharmacotherapy according to guideline on treating chronic heart failure(CHF) in real world clinical practice. A total of 231 consecutive outpatients with reduced left ventricular ejection fraction (LVEF ≤ 40%) and enlarged left ventricular end diastolic diameter (male > 55 mm, female > 60 mm) were recruited from January 2001 to June 2009. All patients were treated with optimal pharmacotherapy according to guideline recommendations and followed up to December 31, 2009. Mortality, rehospitalization and changes of heart size and cardiac function at baseline and at the end of follow-up period were analyzed. (1) 14 patients were lost during follow-up (6.1%), and follow-up was complete in 217 patients (93.9%). 97.2% and 98.2% patients were prescribed angiotensin converting enzyme (ACE) inhibitors and β-blockers (βB). Combined of ACE inhibitors and BB use was applied in 95.3% patients. The target dose of ACE inhibitors and βB were reached in 50.7% and 37.3% patients. (2) Lower mortality and re-hospitalization rates were observed in this cohort: all-cause morality, average annual mortality was 11.5% and 3.9% respectively. Re-hospitalization rate was 27.6%. (3) Left ventricular end-diastolic diameter (LVEDD) decreased from (68.2 ± 7.2) mm to (62.2 ± 9.6) mm. LVEDD value was normal or near normal (male ≤ 60 mm, female ≤ 55 mm) in 43.2% patients. LVEF improved form (29.8 ± 7.5)% to (43.3 ± 11.8)%, LVEF was > 40% in 60.4% patients, LVEF was ≤ 40% but increased ≥ 10% after treatment in 22.9% patients. Optimal pharmacotherapy according to guideline can improve prognosis of outpatients with CHF.