Те, которые у нас дома -  не совместимы, но полагаю что все зависит от размера блоков. Оль, вот чего нарыла______________________________Are mega blocks compatible with lego?Yes. Depends on the size. - Mini Size are compatible with LEGO DUPLO - Micro Size are compatible with ordinary LEGO bricks _____________________________Это из википедии:Mega Bloks building blocks are compatible with LEGO interlocking building blocks.http://en.wikipedia.org/wiki/File:Mega_Bloks_vs._LEGO.JPG______________________________Yes they are compatible! Mega Blocks Minis are compatible with Lego DuplosMega Blocks Micros are compatible with standard LegosLEGO actually filed lawsuits against Mega Brands and lost. All current sets of Mega Blocks Minis and Micros are compatible with Duplos and standard Legos respectively.http://answers.yahoo.com/question/index?qid=20091124073714AA9O4yS