Chronotherapy is a method of administration of drugs in specific combinations and at specific times, in order to achieve the maximum therapeutic effect with the minimum side effects. It is based on the circadian rhythm and the related changes observed during the 24 hours in cell function and body parameters, such as blood pressure. Several studies have shown encouraging results in comparison with conventional therapy. In cancer case studies better response was observed to chemotherapy administered according to chronotherapy principles, with a reduction of side effects and better quality of life. Chronotherapy has also been shown to contribute to the regulation of arterial hypertension, especially during the night, and to be a predictor for the appearance of cardiovascular complications. The main disadvantages of this form of therapy are the need for individual determination of the circadian rhythm of each patient, and the difficulties of the patients in their compliance with the regimen. Conclusions: Evidence from the treatment of both cancer and hypertension support the concept that chronotherapy has many advantages. There is a need for more randomized studies with larger samples of patients in order to document the possible advantages of chronotherapy for wider clinical practice.