THE INVENTION RELATES TO SUBSTITUTED 4-(TETRAZOL-5-YL)-QUINAZOLINE DERIVATIVES OF THE FORMULA-I, OR PHARMACEUTICALLY-ACCEPTABLE SALTS THEREOF, WHICH POSSESS ANTI-PROLIFERATIVE ACTIVITY SUCH AS ANTI-CANCER ACTIVITY AND ARE ACCORDINGLY USEFUL IN METHODS OF TREATMENT OF THE HUMAN OR ANIMAL BODY. THE INVENTION ALSO RELATES TO PROCESSES FOR THE MANUFACTURE OF SUBSTITUTED 4-(TETRAZOL-5-YL)-QUINAZOLINE DERIVATIVES, TO PHARMACEUTICAL COMPOSITIONS CONTAINING THE COMPOUND AND TO ITS USE IN THE MANUFACTURE OF MEDICAMENTS FOR THE PRODUCTION OF AN ANTI-PROLIFERATIVE EFFECT IN A WARM-BLOODED ANIMAL SUCH AS MAN.