The general theory of the chronoamperometric transient for the case of electrochemical nucleation with diffusion-controlled growth has been treated by Scharifker and Mostany [J. Electroanal. Chem. 177 (1984) 13] and Sluyters-Rehbach et al. [J. Electroanal. Chem. 236 (1987) 1]. These models, based on the concept of planar diffusion zones and the use of Avrami's theorem to account for overlap, lead to conflicting results. This paper reports a new general equation for the current transient which is based on elements of both the existing theories. The theoretical predictions of this equation and their relevance for the analysis of experimental transients are discussed and compared with experimental observations.