Background:　To　explore　the　effective　dose　range　of　PHOTOCYANINE,　the　intensity　and　duration　of　irradiation　using　a　670-nm　laser,　and　changes　of　local　tissues　after　photodynamic　therapy　(PDT)　in　mice　with　S180　tumors　to　provide　evidence　for　the　clinical　application　of　PDT.　Basic　methods:　Kunming　mice　were　administered　the　photosensitizer　PHOTOCYANINE.　After　the　administration　of　PHOTOCYANINE,　irradiation　with　670-nm　laser　had　a　remarkable　inhibitory　effect　on　the　growth　of　the　grafted　tumor　S180.　Main　results:　Within　the　power　densities　36-144　J/cm(2),　the　irradiation　dose　showed　a　significant　dose　response　relationship;　under　the　same　drug　dosage,　an　increase　in　irradiation　dose　could　enhance　the　inhibitory　effect　on　tumor　growth.　In　the　groups　administered　PHOTOCYANINE　and　irradiated　with　a　670-nm　laser,　the　temperature　of　the　local　surface　did　not　increase　remarkably,　an　effect　also　seen　in　the　negative　control　group.　Local　swelling　around　the　tumor　occurred　immediately　after　PHOTOCYANINE　administration　and　laser　irradiation,　and　could　last　for　about　3　days.　Vertical　resection　of　the　tumors　72　h　after　irradiation　showed　that　the　depth　of　local-tissue　necrosis　after　PHOTOCYANINE　administration　and　laser　irradiation　was　5.7-7.5　mm.　Principal　conclusions:　The　efficacy　of　PHOTOCYANINE　was　significantly　correlated　with　its　dose;　under　identical　irradiation　conditions,　the　increase　in　drug　dose　increased　the　tumor　inhibition　rate　(TIR)　within　a　certain　dose　range.　The　efficacy　of　PHOTOCYANINE　also　showed　significant　irradiation-dependent　characteristics.　(C)　2010　Elsevier　B.V.　All　rights　reserved.