Field surveys at Kaneohe Bay, Hawaii, indicated higher frequencies of Porites compressa skeletal tumor developments on the reef crest than on the slope. Results of the observation, in which several transects were laid through the reef, showed higher area cover and number of tumors on the reef crest P. compressa colonies. Additionally, when single hemispherical P. compressa colonies were censused for tumors, it showed higher frequencies of tumor developments on the horizontal surface than on the vertical surface. The mean occurrence of the tumors on the horizontal surface was 77.84%, which showed significant difference (P<0.05) from the tumor occurrence on the vertical surface. From the survey, we propose that since the occurrence of the tumors on P. compressa were higher on surfaces that faced higher irradiance levels, the causation of tumors might be related to the level of irradiance that P. compressa receives.