Mangroves support a diversity of the aquatic life including algae. Mangroves provide support to algal epiphytes, thriving on its roots and trunks, while epiphytes provide food for the primary consumers and are reported to be a sustainable contributor to the marine environment. In this study, identification of macroalgae associated with mangrove pneumatophores was conducted at three stations in the Iloilo River, Iloilo City, Philippines, from the month of January to March 2018. Two groups of macroalgae; Rhodophyta (Caloglossa ogasawaraensis, Bostrychia scorpioides) and Cholorophyta (Chaetomorpha crassa, Ulva reticulata) were found to be growing on the pneumatophores of Avicennia rumphiana. The physico-chemical parameters of the water in the study area vary in terms of salinity, pH, and temperature. Caloglossa ogasawaraensis and Chaetomorpha crassa were found in all three sampling stations with varying conditions of salinity, pH and temperature, hence are generalists. Ulva reticulata tolerated condition of higher temperature, while Bostrychia scorpioides were found only in condition of very high salinity. Thus, physico-chemical parameters influence the distribution of macroalgae in Iloilo River. It is further recommended that studies on diversity of macrophytes associated with mangroves and abundance of macroalgae in various mangrove sites in Iloilo be done.