This study determined the effect of supplementing fermented soybean curd residue juice (FSCRJ) on the growth performance (average daily gain, growth rate, feed conversion ratio) of Pekin ducklings; assessed carcass quality; checked for the presence of gross liver and intestinal lesions; and obtained a cost and return analysis. Ninety male Pekin ducklings, were randomly distributed into five (5) treatments: Treatment | with pure water (control): Treatments 2 to 5 with 20ml, 30ml, 40ml and 50m! of FSCRJ, respectively and were replicated three (3) times. Growth performance parameters were compared using one-way analysis of variance (ANOVA) in completely randomized design (CRD) while Tukey's Test (HSD) compared the treatments means. Kruskal-Wallis Test was utilized to identify the significant difference on the breast dimensions. Results revealed that, Treatment 5 had the highest final weight (3119g), gain in weight (2581.67g), average daily gain (43.02g) and the lowest feed conversion ratio (2.79). Supplementation of FSCRJ showed no significant difference in carcass quality, and revealed gross intestinal (hemorrhages and erosion) and liver (hemorrhages, pale discolorations, fibrosis) lesions. Treatment 5 was more cost effective than other treatments based on the growth performance parameters. Moreover, inclusion of FSCRJ as an additive was relatively cheaper than using pure commercial feeds. Martija, Shan Wilfred D. 2022 Growth performance of Pekin ducklings supplemented with fermented soybean (Glycine max) curd residue juice. College of Veterinary Medicine, Pampanga State Agricultura] University, Magalang, Pampanga. Undergraduate Thesis. Adviser: Remedios D. San Jose, DVM, DrPH.