Dassù won the 1970 British Youths Open Amateur Championship and played for Italy in that year’s Eisenhower Trophy. He turned professional in 1971 and was a regular on the European Tour from its first official season in 1972 until the mid-1980s. His most successful season by far was 1976, when he won his only two European Tour titles at the Dunlop Masters and the Italian Open, which he won by eight shots, and went on to finish ninth on the Order of Merit. Off the tour he won the Italian Professional Championship in 1974, 1976 and 1977. He represented Italy in the Alfred Dunhill Cup twice and in the World Cup of Golf four times.
As a senior, Dassù played the European Seniors Tour for one season, finishing 26th on the 2003 Order of Merit.
- This list may be incomplete
- 1974 Italian National Championship
- 1976 Italian National Championship
- 1977 Italian National Championship
- 1983 Italian PGA Championship, Open dei Tessali
- 1985 Cerutti Open
- 1988 Open dei Tessali
Note: Dassu only played in The Open Championship.
CUT = missed the half-way cut (3rd round cut in 1972 and 1978 Open Championships)
“T” = tied