Yield potential and response to Ethrel® stimulation of three clones (RRIM 600, PB 235 and GT1) have been studied for two years in Chachoengsao Rubber Research Center (CRRCRRIT-DOA). Trees were tapped using a ½ S d/3 6d/7 tapping system. Physiological parameters (inorganic: phosphorus and sucrose latex contents) were studied in order to characterize the latex metabolic activity and the latex sugar loading capacity of these three clones in a non-traditional rubber growing area (Sanam Chai Khet, Chachoengsao province, Thailand: 1200 mm rainfall/year, 4-5 months of dry season). Results obtained after two years of experiment showed that sugar loading and metabolic characteristics were not modified by this particular eco-climatic context: metabolism of GT1 was medium, metabolism of PB 2:35 was high and metabolism of RRIM 600 was intermediate between GT1 and PB 235 (medium-high). All three clones showed a medium sugar loading capacity (same ability to import sucrose in their laticiferous system, for a given metabolic activity). Yield potential of clones PB 235 and RRIM 600 were found higher than the one of GT1, that cannot therefore be recommended for commercial planting in this area. Nevertheless, it seems worth to keep GT1 as a reference control clone in clone field trials of breeding programs, as GT1 represents a reference both for latex metabolism (medium) and for latex sugar loading capacity (medium). Response to stimulation (dP) was confirmed proportional to sucrose apparent consumption d[Suc], showing again the major role of latex sugar content regarding clonal yield potential.