The shape of rainfall cells is a crucial ingredient of stochastic point-process models that describe intense precipitation events. Here we study the shape of the individual rain cells measured during the TOGA/COARE and GATE radar experiments. We find that, on average, rainfall intensity decreases exponentially from the cell's center. An exponential profile provides a good estimate of the precipitation intensity in the bulk of the cell. By contrast, the standard assumption of a Gaussian shape leads to significant underestimation of the precipitation intensity in the central portion of the cell and of the associated hydrologic response.