OBJECTIVES: Current guidelines recommend a combination of ACEIs/ARBs, beta-blockers and aldosterone antagonists for the treatment of chronic heart disease; however, previous studies have found minimal use of these medications. This study aimed to evaluate the physicians’ adherence to treatment guidelines and to explore the association between adherence to guidelines and re-hospitalization in patients with chronic heart failure in Thailand. METHODS: This retrospective cohort study collected data from systolic heart failure patients who received treatment from a tertiary university-affiliated hospital between January 2008 and December 2010 and were followed-up for 2 years.  The evaluation of the physicians’ adherence to treatment guidelines in prescribing ACEIs/ARBs, beta-blockers and aldosterone antagonists (primary endpoint) were conducted by using a Guideline Adherence Indicator (GAI-3; classified as low, medium and high) according to the recommendation of guidelines. The secondary endpoint was re-hospitalization for CHF during the follow-up period.  RESULTS: Of 155 patients, more patients were prescribed beta-blockers (65.8%) than ACEIs/ARBs (50.7%) and aldosterone antagonists (20.0%). Twenty-five, 47 and 28 percent of patients were classified as low, medium and high GAI-3, respectively. The rate of re-hospitalization was lower in patients with a high GAI-3 score compared to patients with a medium or low GAI-3 score (79.1 vs. 90.4 vs. 94.9, per 100 person-years, respectively). Multivariable Cox regression analysis (adjusted by sex, age, NYHA Functional Class and comorbidity) found that patients with high and medium GAI-3 scores had a lower risk of re-hospitalization compared with low GAI-3 score (high GAI-3 score:adjusted HR 0.184, 95%CI:0.093-0.367,p<0.001; medium GAI-3 score: adjusted HR 0.436, 95%CI:0.238-0.797,p=0.007). CONCLUSIONS: Physicians’ adherence to treatment guidelines for systolic heart failure was not optimal. Some patients did not receive medications following the guidelines’ recommendation.  Our results suggested that using medications following treatment guidelines was an important factor to reduce the risk of re-hospitalization from heart failure.