Thirty novel 5-(3-(substituted phenyl)-4,5-dihydroisoxazol-5-yl)-2-methoxyphenyl derivatives were synthesized and evaluated for their antitumour activity. The bioassays showed that the 2-fluorobenzoyl derivative 6ai, the 4-trifluoromethylbenzoyl derivative 6ah, and the 3-trifluoromethyl isoxazole derivatives (6ch and 6ci) were highly effective against PC-3 cells. The IC50 values of 6ah and 6ai against PC-3 cells were 1.5 and 1.8 μg mL–1, respectively.