The pool sizes of adenylates, Adenosine 5 tri phosphate (ATP), Adenosine 5 diphosphate (ADP) and Adinosine 5 monophosphate (AMP) in latex, lutoid membrane ATPase activity and cytosolic pH in two high yielding and two low yielding clones were studied during November/December and March/April. There was a strong correlation among concentration of ATP in latex, lutoid membrane ATPase activity and cytosolic pH and all these three parameters were significantly higher in the two high yielding clones than the two low yielding clones during November/December. When measured during summer (March/April), concentration of ATP in latex remained significantly high in the high yielding clones, but lutoid membrane ATPase activity and cytosolic pH gave inconsistent results possibly due to enhanced lutoid disruption, which affected the enzyme activity and cytosolic pH. It is suggested that a large supply of ATP made more energy available for rubber biosynthesis and also it activated the lutoid membrane ATPase activity and thus regulated the cytosolic pH to more optimal levels(less acid) for better conversion of sugar into polyisoprene. The possibility of utilising ATP concentration in latex as an indicator of high yield is discussed.