Objectives: 1) to study normal values of the ratio between systolic and diastolic durations (SID) in adults and 2) to study the relationship between the SID ratio with some clinical and Doppler echocardiographic parameters in the normal adult. Subject-Methods: 57 healthy people, no heart disease were examined by dinically detailed, blood tests, electrocardiograms, heart - lung X-ray. Research the flow through the tricuspid valve by Doppler ultrasound from the apical 4-chamber view. Systolic duration (S) was defined as the duration of holosystolic tricuspid regurgitation (includes both the isovolumic contraction and relaxation times). The diastolic interval (D) was defined as the period between 2 tricuspid regurgitant jets, from which, calculated the SID ratio. The values (mean + or - SD) of the ratio SID of all subjects, male and female, of the over and under 50 years old was calculated and compare the difference of the ratio SID in these groups. Set the linear correlation between SID with the clinical and echocardiographic parameters. Results-Conclusion: the average value of the ratio SID in adults in age from 18 to 81 (mean 48.9 + or - 15.3) was 0.75 + or - 0.14. No difference in the ratio of SID between men and women and no difference in the ratio of SID between people under 50 and people aged 50 years or older. The ratio of SID is linearly correlated well with heart frequency (r = 0.5, p 0.05). No linear correlation between the ratio of SID and age.