A sequential study desccibing the content (%) of aalkaloids in leaves of Erythroylum ccoca var. coca Lam. from leaf bud develpment to loeaf drop has not previously been conductedd. In the present study cocaine was highest in 7 day old rolled leaves (0.75%) and eclined to 0.39% at lleaf drop. All the monitored allkaloids appeared to be part of the metobolically active pool of the leaf. Leaves remain on the E. coca plants for 36 weeks.