Surveys for lesions in corals were conducted at seven sites around Tutuila in June 2004 and January 2005. The objectives of the study were to document the distribution and prevalence of disease in the major genera of corals and crustose coralline algae, systematically describe gross and microscopic morphology of lesions in reef corals and determine whether there are seasonal differences in prevalence of disease. We documented 12 different coral disease states from the reefs of Tutuila and two diseases of crustose coralline algae (CCA). Acropora white syndrome, Acropora growth anomalies and coralline lethal orange disease were the most common diseases on the reefs of Tutuila. No seasonal differences were found in overall prevalence of coral or abundance of CCA disease. Histological analyses of coral lesions revealed that microscopic changes in tissues can be used to distinguish tissue loss due to trauma from changes due to disease, detect micro-organisms associated with certain types of discolorations and found that hyperplasia of the basal body wall was the hallmark microscopic appearance of Acropora growth anomalies regardless of gross morphology of tumors.