  Q-balls arise in particle theories with U(1) global symmetry. The coupling of
the corresponding scalar field to fermions leads to Q-ball evaporation. In this
paper we consider the oposite problem, the case where a Q-ball absorbs
particles to grow. In particular we shall use the exact quantum mechanical
description of fermions interacting with a Q-ball to solve the problem. Results
show that Q-ball condensation can be another mechanism for Q-ball creation.
