The ‘Philippine Lono Tall’ (PLNT) is a variant of the more common ‘Philippine Laguna Tall’ (LAGT), which produces fruits with soft endosperm and reported higher fat content. To understand patterns of fatty acid (FA) and oil accumulation in LAGT and PLNT fruits, transcriptomes of 6–7 month-old endosperm samples were analyzed by RNA-Seq. Quantitative PCR was performed to analyze the differential expression of selected genes related to oil biosynthesis. Further, oil samples from the PLNT endosperm were analyzed to determine their FA composition across developmental stages.