Heterojunctions　combining　two　photocatalysts　of　staggered　conduction　and　valence　band　energy　levels　can　increase　the　photocatalytic　efficiency　compared　to　their　individual　components.　This　activity　enhancement　is　due　to　the　minimization　of　undesirable　charge　recombination　by　the　occurrence　of　carrier　migration　through　the　heterojunction　interface　with　separated　electrons　and　holes　on　the　reducing　and　oxidizing　junction　component,　respectively.　Metal-organic　frameworks　(MOFs)　are　currently　among　the　most　researched　photocatalysts　due　to　their　tunable　light　absorption,　facile　charge　separation,　large　surface　area　and　porosity.　The　present　review　summarizes　the　current　state-of-the-art　in　MOF-based　heterojunctions,　providing　critical　comments　on　the　construction　of　these　heterostructures.　Besides　including　examples　showing　the　better　performance　of　MOF　heterojunctions　for　three　important　photocatalytic　processes,　such　as　hydrogen　evolution　reaction,　CO2　photoreduction　and　dye　decolorization,　the　focus　of　this　review　is　on　describing　synthetic　procedures　to　form　heterojunctions　with　MOFs　and　on　discussing　the　experimental　techniques　that　provide　evidence　for　the　operation　of　charge　migration　between　the　MOF　and　the　other　component.　Special　attention　has　been　paid　to　the　design　of　rational　MOF　heterojunctions　with　small　particle　size　and　controlled　morphology　for　an　appropriate　interfacial　contact.　The　final　section　summarizes　the　achievements　of　the　field　and　provides　our　views　on　future　developments.　The　present　review　summarizes　the　current　state-of-the-art　in　MOF-based　heterojunctions　in　three　important　photocatalytic　processes:　hydrogen　evolution　reaction,　CO2　photoreduction　and　photodegradation　of　dyes.