In situ (nylon bag) technique was used to investigate the effects of forage pH level and rumen pH manipulation on rumen degradability of foliages from selected trees and shrubs. Six forages - Kakawate (Gliricidia sepium), Madre de agua (Trichanthera gigantea), Acacia (Samanea saman), Gmelina (Gmelina arborea), Robles (Cassia siamea) and Santol (Sandoricum koetjape) - were analyzed for their pH level and were categorized as low, medium and high pH; consequently, two samples in each category were used in the study. The study was set-up in a completely randomized design. The pH level of forages significantly influenced dry matter disappearance (DMD) in the first 24 hours of incubation, such that forages with medium to high pH levels generally showed higher values than those with low pH levels. The DMD after 48 hours of incubation appeared to be more affected by the characteristics of the forages influencing degradability rather than their pH levels. The addition of acetic acid to bring the rumen pH into an ideal level of 6.0-6.4 increased DMD, indicating the beneficial effects of rumen pH manipulation on forage digestibility.