Many studies have been conducted to help understand the effects of the variables involved in jet milling. The first part of this work is an attempt to summarise the results published in the literature concerning horizontal and vertical jet mills. This focuses on the research of the optimal design of the mills and on the improvement of their performance. Several publications have been found, concerning mineral grinding. It seemed more interesting to present results on organic crystals' jet milling in the second part of this paper. The experiments concern three organic substances, and were run on three different spiral jet mills: Chrispro-Jetmill 50 and 100 and MicronMills 8 ". The results are presented in terms of specific energy consumption with an adaptation of the correlation proposed by Sarma. These representations show that, within the operating energy range and above a critical energy value, the creation of specific surface area corresponds to an increase of fine particles production.