A 30-fold increase in the quantum yield of fluorescence of pseudoisocyanine (PIC) J-aggregates in the vicinity of CdTe nanocrystals has been revealed as a result of the resonant energy transfer from the nanocrystals to PIC J-aggregates in aqueous solutions. This enormous effect was accompanied by rather modest (similar to 30%) energy transfer efficiency and was assigned to rearrangement in the J-aggregate structure where the increased number of participating molecules in the J-aggregate coherence domain was calculated. No energy transfer was observed when the J-aggregate antenna size was small. The antenna size was found to be controlled by pH of the solution. (C) 2012 Elsevier B.V. All rights reserved.