A series of benzyloxybenzaldehyde derivatives were prepared and tested against the HL-60 cell line for anticancer activity. Preliminary structure–activity relationships were established. It was discovered that 2-(benzyloxy) benzaldehyde (17), 2-(benzyloxy)-4- methoxybenzaldehyde (26), 2-(benzyloxy)-5-methoxybenzaldehyde (27), 2-(benzyloxy)-5- chlorobenzaldehyde (28), 2-[(3-methoxybenzyl) oxy] benzaldehyde (29), 2-[(2- ...