In coral reefs, competition between sessile benthic organisms for access to space and other resources is a determining factor in community structuring. Recent coral mortality has favored the development of algal turfs, which are now competing with corals, often displacing them,although slowly. To determine the frequency of interactions between coral-turf and coral-other benthic categories, and how their distribution and results (coral wins or coral loses) are modulated by environmental factors, band photo transects were evaluated for 12 stations in the ParqueNacional Natural Tayrona, Santa Marta, Colombian Caribbean. It was found that algal turfs are the most frequent competitors of massive corals, and that the frequency of coral-turf interactions depends on the particular susceptibility of a coral species to the loss of tissue, and past disturbances that have affected the reef in which it lives. Furthermore, the results of these interactions depend on the ways the colonies are organized, meandroidand cerioid colonies being the most successful in competition against turfs, as their vertical growth constitutes an effective avoidance mechanism. By contrast, plocoid colonies are more prone to lose. In general, biological factors (the coral species in question and type of colonial organization) were determinants in the frequency and apparent result of coral-turf interactions, while environmental factors (disturbance gradient, depth, anddegree of wave exposure) appear not to play a predominant role. As a consequence, historical and future changes in coral species cover, and the nature of colony organization in the Santa Marta area, should reflect a combination of their susceptibility to deleterious agents and their capacityto counteract or evade competition, especially with algal turfs.