The study was conducted in San Nicolas 1*, Magalang, Pampanga, from March 10 to July 16, 2021. It aimed to determine the field performance of Bagras/Rainbow eucalyptus (Eucalyptus DegluptaBlume.) seedlings applied with different levels of NPK fertilizer under climatic type I condition. A total of 120 seedlings were used. The experiment was laid out in Randomized Complete Block Design (RCBD) with four treatments. Treatment | (control/no treatment), Treatment 2 [recommended rate 5Sgrams of Urea (46-0-0) and 45 grams Muriate of potash (0-0-60)}, treatment 3{ 25% higher than the recommended rate 69 gram of Urea (46-0-0) and 56 grams of muriate of potash (600-0)], treatment 4 [25% lower the recommended rate 41 grams of Urea (46-0-0) and 34 grams muriate of potash (0-0-60)]. Every treatment was replicated three times. Ten (19) sample plants were used per treatment. Based on the result of the study, it was revealed that the application of different levels of NPK fertilizer has a significant effect on the field performance of bagras (Eucalyptus degluptaBlume) seedlings under climatic type 1 conditions. Significant findings were observed on plant height increment 45 and 75 days after fertilizer application in T4; highly significant results were observed on diameter increment at 45, 60 and 90 days on plants in T3 and T4; and significant result on number of leaves 60, 75 and 90 days after fertilizer application were observed in T3. One hundred percent survival was observed in T2 and T4.