A computer simulation technique is applied to the modelling of Balmer line shapes in dense divertor conditions. The spectral profile of lines with a high principal quantum number n is sensitive to Stark broadening and can be used as a density diagnostic. In contrast, an analysis of the shape of low or moderate n lines such as D (n = 3), D (n = 4), and D (n = 5) is more intricate because the Stark effect is weaker and can compete with thermal Doppler broadening. We examine this issue and address the relative contribution of the Stark and Doppler effects on the first Balmer lines. Analyses of experimental spectra are performed.