OBJECTIVES: Different meteorological factors can play a role in the occurrence of cardiovascular diseases. Whether certain meteorological and astronomical factors, and the periodical change influence the bleeding quantity after heart operation. METHODS: Retrospective analysis was made on the University of Pécs Cardiotherapy Clinic among patients went through heart operation (n=611) between 2007.01.01 and 2007.12.31. in Hungary. Statistical tests: khí2 test, variance analysis (ANOVA), Pearson-Spearman correlation coefficient examination was made. Data processing was done with SPSS 15.0 and MS Excel programs. RESULTS: No connection was found between the examined meteorological factors and the quantity of total bleeding but on the other hand we found connection between the energy of the solar flares and the daily average bleeding (p=0.025). Significant values were found between the periodical change and total bleeding (p=0.03). CONCLUSIONS: Postoperative bleeding is influenced by many factors: antecedents of patients, atmosphere and cosmic factors, perioperative medication, operative data, surgical technique. The examined factors do not affect the bleeding quantity, on the other hand certain astronomical factors do. The energy of the solar flare showed a negative correlation with bleeding. The periodical change influences postoperative bleeding among patients with open heart operation.