He made his Scotland debut (at the age of 22) against France in 1978 when Scotland lost, 16 - 19. He was active on the national team between 1978, and 1987, with his high point being in Scotland's 1984 Grand Slam.
Richard Bath writes of him that he was
"The prototype for the faster hooker, acting as an extra flanker that has since emerged, Deans has few equals. Superb in the loose and a wonderfully quick striker of the ball in the scrum, the rugged Deans was also a pinpoint line-out thrower."
Allan Massie describes him as a hooker with back-row skills:
"He is the most remarkable loose forward of any hooker I have seen. There can have been few, if any, faster; indeed, his speed is such that from the broken play and the line-out he gives Scotland in effect a fourth back-row forward. This means that, like Carmichael, he is ideal for the modern game, capable of fulfilling his specialist role, but also of taking a full part in fifteen-man Rugby. He harries the defence tirelessly: in the great win at Cardiff in 1982 Deans had a big part in the build-up for two of the Scottish tries; he was also at Calder's shoulder to take a pass, had that been necessary, when the first try was scored."
He also says that Deans was, "with the possible exception of Peter Wheeler, the most accurate thrower-in of recent years."
He obtained 52 caps for his country. He is said to have been most effective when playing in combination with David Leslie.
Noted for his skills at the line-out, of the game against Wales in 1984, the first Scottish Grand Slam since 1925, Allan Massie says "we would have probably lost that game if the Deans-Leslie combination had been less effective".
Note 1: Robert Seddon died on tour after a boating accident, Andrew Stoddart, became captain for the remainder of the tour. Note 2: Matthew Mullineux decided that after losing the first test that he should withdraw from further test matches, handing on field captaincy to Frank Stout, but remained tour captain. Note 3: David Bedell-Sivright was injured during the first test. Teddy Morgan took over captaincy on the field but Bedell-Sivright remained tour captain. Note 4: The team that John Raphael captained was not selected by the four Home Nations governing body, but had been organised by Oxford University and billed as the English Rugby Union team. However, it was denoted as the Combined British team by its Argentine hosts because it also included three Scots. Note 5: Jack Jones captained the first test only, but Tommy Smyth remained the tour captain. Note 6: Michael Owen captained the Lions in the first tour game, the test vs. Argentina in Cardiff. Brian O'Driscoll was injured at the beginning of the first test. Martin Corry and Gareth Thomas took over captaincy on the field but O'Driscoll remained tour captain.