SYNOPSISEarly research trials in South Africa have shown that Eucalyptus species generally respond positively to the addition of nutrients at planting. However, as most of these research trials were located in KwaZuluNatal, it was important to investigate the nature of the response in other afforested regions of the country where this genus is planted. Consequently, a number offertilizer trials were established in the late 1980's and early 90's in Mpumalanga and the Northern Province to investigate the nature offertilizer responses in Eucalyptus species. Three of these trials form a series and were established to investigate the impact of nitrogen (N), phosphorus (P) and potassium (K) additions made both individually and in combination. In addition, two trials in Mpumalanga were initiated to investigate genotype by fertilizer interactions. Viewed as a whole, the results indicate that growth improvements in response to the nutrient additions are readily obtainable. Highly significant positive responses to Nand P, each applied individually, occurred immediately after planting. The response to N appeared more sustained than the response to P. The best growth was observed when Nand P were applied together. The ratio ofN to P that gave the best response ranged from 3:1 to 3:2. No genotype by fertilizer interactions were observed in the trials investigating this aspect.