The seasonal prevalence and vertical distribution of oviposition of Aedes aegypti were studied for 53 wk in 1999--2000 using modified ovitraps located at several elevations. The ovitraps were positioned both indoors and outdoors in high-rise apartments in the urban township of John John, Port of Spain, Trinidad, West Indies. Of 988 ovitraps, 490 were collected during the months of the wet season, with 404 (84.4%) positive with 18,536 Ae. aegypti eggs. Of 498 ovitraps collected during the dry season, 335 (67.3%) were positive with 12,255 Ae. aegypti eggs. Data from different elevations showed that significantly more eggs were collected at 13-24 m elevations than any other elevation. The results suggest that the invasion of high rise ecosystems by Ae. aegypti can enhance transmission of dengue. This ecological shift in the Ae. aegypti population exploited new habitats associated with human activity, suggesting that strategies should be developed to educate householders as well as creating appropriate vector control measures to prevent future threats of dengue transmission.