The Academy of Sciences of the Czech Republic has been observing the 20th anniversary of its inception. This month we feature an interview with Professor Helena Illnerová of the Institute of Physiology of the ASCR, the first woman to be elected president of the ASCR. Professor Illnerová is one of the leading Czech scientists, having begun her work in the 1960s. Her main research interest is the time-keeping program of mammals, including man, and the synchronization of the circadian biological clock with the 24-hour-day and seasons of the year. In 1990, she received a DrSc. degree for a doctoral thesis entitled Regulation of Circadian Rhythms in the Rat Pineal Gland.