Abstract. For an acute-angled triangle ABC , we construct two isotomic points P and Q on BC and P ′ and Q′ on AB and AC respectively, such that BP P ′ and C QQ′ are right triangles which, when rotated about P ′ and Q′ respectively through appropriate angles fit with AP ′ Q′ to a quadrangle with a new fourth vertex A′ . We show that AA′ passes trough the circumcenter O.