Pumpkin ( Cucurbita pepo
Linn.) is a vegetable crop often grown without fertilizer by peasant farmers in Nigeria. With the increased pressure on land resources for other competing uses, farmers have adopted the use of fertilizers to boost crop productivity. This study was carried out for the purpose of evaluating the influence of NPK fertilizer on fruit yield and fruit yield parameters of pumpkin. The experiment was carried out under open field conditions in 2010 for two seasons at the Teaching and Research Farm, Obafemi Awolowo University, Ile-Ife, Nigeria. The farm is located on latitude 07°28’N and longitude 04°33’E about 244-m above sea level. NPK 15:15:15 compound fertilizer was applied as ring/side dressing at the rates of (0, 50, 100, 150, 200, 250 kg/ha). The experiment was a randomized complete block design and was replicated six times. Each plot size was 10 m X 12 m and consisted of 7 rows. Alley was 3 m, while the plants were spaced 2 m x 2 m. Data were taken on yield and yield parameters such as: fruit height, fruit circumference, fruit fresh weight, fruit dry matter, fruit yield, seed number and seed weight. The fresh fruit yield was 21 t/ha and 7t//ha for early and late seasons, respectively. Fruits number/ha significantly (p=0.05) increased from 7000 in control to over 10,000/ha at fertilizer rates between 100 and 250 kg NPK/ha. Fruit weight also increased from 9 to 17t/ha between control and higher fertilizer rates. Seed yield from the application at 100 to 250 kg/ha were similar and significantly better than control and 50 kg/ha NPK application. Mean seed yield between 100-250 kg NPK was 460 kg/ha. The value was 37% higher than at 50 kg NPK and 57% higher than in control. Increasing fertilizer above 100 kg NPK/ha did not significantly (p=0.05) increase the fruit yield nor the seed yield.