Many vegetable crop plants, including tomato, have high water needs and one of the options to overcome the negative effects of water reduction on yield is the use of deficit irrigation methods. Detailed knowledge on the effects of different irrigation methods on fruit developmental processes could be a critical factor in the analysis of the effect on final yield. It is well known that water reduction limits the fruit growth rate and final fruit size in tomato, as a consequence of impact on cell division and expansion processes. This paper reviews roles of cellular traits in the responses of tomato fruit growth to deficit irrigation (DI) which were assessed using the wild type (WT) and its flacca mutant deficient in plant hormone abscisic acid (ABA). We specifically addressed how the cell number, cell size and setup of pericarp cell layers were affected by water deficit during development. Fruits of flacca in optimal irrigation are smaller as a consequence of smaller-sized cells in the pericarp. DI induced a stronger negative effect on cell division and expansion in flacca than in WT at an early stage. However, the effects of DI were similar in flacca and WT in ripe fruits. The main difference between flacca and WT responses to water restriction was a stronger negative impact during the early cell division in flacca, which is consistent with the involvement of ABA in the cell division process and water-stress-induced ABA synthesis in WT.