In the World Chess Championship cycles, Portisch played in every Interzonal from 1962 to 1993, twelve in total. He qualified for the next stage, the Candidates Tournament, eight times: in the 1966, 1969, 1975, 1978, 1981, 1984, 1987 and 1990 cycles; with his best results when he reach the Candidates semi-finals in 1977 and 1980.