The study was carried out in the greenhouse of the ";;;Instituto Agronomico de Pernambuco - IPA";;;, located in Recife - PE. It aimed to evaluate the effects of P and K fertilization on growth and chemical composition of cactus pear IPA-20 clone. Four levels of P (0, 200, 400, and 800 kg P 2 O 5 ha -1 ) and four levels of K (0, 200, 400, and 800 kg of K 2 O ha -1 ) were tested in a 4 x 4 factorial arrangement using a complete randomized block design. Observations were made at 28-d intervals, starting by the third month after planting and lasting until the sixth month of growth. Fresh matter yield of primary articles and total fresh matter yield were affected only by K fertilization (P -1 , respectively. Fresh matter yield and dry matter concentration were affected only by K fertilization. Micronutrient concentration was not affected by P and K fertilization.