This study was designed to gain insight into the influence of spraying and cooling, during artificial incubation, on the embryo metabolic rate and hatching ability of Muscovy duck eggs. Three times a week 93 incubated eggs were sprayed and cooled for 0.5 h at room temperature. Daily embryo metabolic rate was measured in 30 eggs with a water vapor conductance ranging from 1.15 to 2.07 mg/day-kPa. Egg weight ranged from 63.73 to 84.52 g; length and breadth ranged from 59.6 to 66.4 mm and 43.2 to 48.2 mm, respectively. According to observed hatching ability, eggs were classified by three categories: eggs that hatched normally; eggs that were assisted during hatching, and nonhatched eggs. Five ducklings were assisted during hatching. Four ducklings died on Day 31, two on Day 32, and two on Day 34. Two functions were derived by discriminant analysis and accounted for 100% of the variation among the three categories of hatching ability. Collectively, these functions were able to classify 93.3% of the eggs in the correct hatching category. Egg length and metabolic rate at Days 21 and 28 of incubation were the most important predictor variables of the two functions. The results obtained in the present study indicate that an incubation temperature of 37.5 C with spraying and cooling seems to be beneficial for larger eggs.