Nutrient deficiency in an annual crop like cantaloupe should be detected early in the season, so it can be corrected as soon as possible during the crop cycle. The objective of the present work was to determine the optimum date for foliar sampling for nutrient analysis, based on the best estability of nutrient concentration throughout the crop cycle. Results indicate that there is a significant difference and more variation in the four foliar sampling for the foliar concentration of most of the nutrients (nitrogen, phosphorus, potassium, calcium, magnesium, iron, zinc and boron) except for manganese and copper. The period with less variation and therefore the more appropiate for foliar sampling was between 46 and 65 days after planting and it goes from the beginning of hermafrodite blooming to young fruit, wich implies 570.45 to 860.16 degree day. By sampling in this season, it is possible to correct nutrient deficiency during the crop cycle. Potassium and magnesium were the most deficient nutrients in this period of foliar sampling.