Determinations of nitrogen (N) and chlorophyll (Chl) by destructive methods are precise but time-consuming and frequently expensive. The objective of this study was to determine the relationship between SPAD, atLEAF, and MC-100 readings with the concentrations of Chl, N, and fresh matter (FM) in basil 'Nufar'. In addition, we determined the relationship of the N concentration with fresh matter (FM). The plants were irrigated with five levels of N (0, 4, 8, 12, and 16 mEq·L-1 of NO3) based on a modified Steiner solution for 42 days after transplant. Plants were evaluated weekly with SPAD, atLEAF and MC-100 portable chlorophyll meters in the greenhouse, while fresh matter and the concentration of chlorophyll and N were determined in the laboratory using conventional techniques. The relationship between SPAD readings, Chl, N, and FM was strong, positive, linear, and significant, with correlation coefficients (R2) between 0.94 and 0.98. For atLEAF and MC-100 readings, R2 values were 0.96 to 0.99 and 0.96 to 0.99, respectively. The relationships between SPAD, atLEAF and MC-100 readings were strong, positive, and significant, with R2 values of 0.98. Similar behavior was shown by the relationship of N concentration and FM with R2 of 0.88. With these results, we conclude that SPAD, atLEAF, and MC-100 can be used to estimate the nutrient status of N in a non-destructive, rapid and reliable manner during basil production.