The human biological mechanisms show a predictable clinical variability in time, which has allowed a deeper reevaluation of present-day medical practices, regarding the circadian rhythm (CR) and the mechanisms that produce the supported variations in all biological levels. We have made a study aiming to relate the CR and onset of the neurological clinic situation due to the encephalic vascular lesion, correlating with modifying risk factors. Fifty three patients were studied, 50,94% female (n=27) and 49,50% male (n=26), at average age 66.4 years old. Four intervals of six hours each (0-6; 6-12; 12-18; 18-24) were used to analyze the frequency of the ictus and the incidence in each interval. We found an incidence of 6(11.32%) patients in the 0-6 hs interval; 21 (39.62%) patients in the 6-12 hs interval; 10(18.86%) patients in the 12-18 hs interval; 16 (30.18%) patients in the 18-24 interval. A correlative study with the risk factors has shown that arterial hypertension [(81.25%)] and smoking habit [ (56.25)] were predominant during the 18-24 hs interval, while sedentary [11(52.38%)] stress [11(52.38%)] diabetes [(47.61%)] hyperlipidemia [8 (38.09%)] and alcoholism [8 (38.09%] were predominant during the 6-12 hs interval; and cardiac diseases in the 12-18hs interval.