The 1966 season proved to be the best of her career. She set a championship record of 54.3 seconds to win her second national title in the 400 m. Her focus for the season was the 1966 European Athletics Championships, held in Budapest. In the first round she set a new national record of 53.6 seconds – the first time a Czechoslovak woman had run the 400 m under 54 seconds. She progressed to the final and produced a lifetime best performance of 52.9 seconds to hold off home favourite Antónia Munkácsi by a small margin, with both athletes recording the same time. She ranked second in the world that year, behind only Australia's Judy Pollock, who was the world record holder for the 440 yards at the time. She was the first person from Slovakia to win gold at the competition. At the European Championships she was subject to a new procedure: she had to undergo a sex check by a panel of women doctors, in line with new rules set by the International Amateur Athletic Federation that year.