This is the second in a series of studies that aim to provide a comprehensive overview of the morphological diversity of Mymaridae (Hymenoptera) or fairyflies, a monophyletic family of small parasitic wasps postulated to be the sister group of all other Chalcidoidea. The external morphology of the mesosoma of about 65–75 taxa, representing 55–65% of the 115 currently valid described genera and subgenera, is described and illustrated with almost 269 scanning electron micrographs, including 77 micrographs of the dorsal, 71 micrographs of the lateral, 59 micrographs of the ventral, 53 micrographs of the anterior, and 9 micrographs of the posterior views of the mesosoma. Twenty annotated figures of the external and major internal structures are given. Two appendices list the morphological terms used, and names of the 75 genera and subgenera of Mymaridae illustrated. The variety of characters and their features that could be used to help define morphologically the genera, and possibly also the species, of Mymaridae is discussed.