Influence of different girth at opening for tapping (40, 45, 55, 60 and 65 cm) of Hevea brasiliensis trees belonging to three dones viz., GT 1, PB 217 and PB 235 on growth, yield and physiological function were studied over a period of ten years in South Eastern Cote d'Ivoire. Opening girth of 40-50 cm for the clone GT 1 and 50 cm for PB 217 and PB 235 was observed to be ideal. This girth achieved at six years after planting corresponded with the physiological maturity of Hevea.