Dormancy is displayed by several organisms when environmental conditions cannot support their regular life activities. Numerous aquatic invertebrates survive for decades in a hydrated state as encysted embryos. In search for functional pathways that are associated with this form of dormancy, we used label-free quantitative proteome profiling and compared the proteomes of encysted dormant embryos (“resting eggs”; RE) with non-dormant embryos (amictic eggs; AM) of the rotifer Brachionus plicatilis. We also compared resting eggs (RE) before and after an obligatory dormant period (E0). A total of 2,631 proteins were identified in AM, RE and E0 eggs. Significantly lower numbers of proteins were determined for RE and E0, compared with AM. About 80% of the proteins were upregulated in AM, in the comparisons of AM vs. RE and AM vs. E0. The differentially expressed proteins were assigned to a large number of putative functional pathways, demonstrating the dramatic changes occurring during dormancy.