The moulting cycles of all larval stages (zoea I, zoea II, megalopa) of the spider crab Maja brachydactyla Balss 1922 were studied in laboratory-reared individuals. Changes in the epidermis and cuticle were photographically documented in daily intervals and assigned to successive stages of the moulting cycle (based on Drachs classification system). Stage characterizations were mainly based on microscopical examination of integumental modifications in the telson, using epidermal condensation, apolysis, the degree of epidermal retraction, and morphogenesis (setogenesis) as criteria. In the zoea II and megalopa, the formation of new setae was also observed in larval appendages including the antenna, maxillule, maxilla, second maxilliped, pleopods, and uropods. As principal stages within the zoea I moulting cycle, we describe postmoult (A-B), intermoult (C), and three premoult stages (D0, D1, D2). In the zoea II and megalopa, stages stages D1 and D2 had to be combined, because morphogenesis (the main characteristic of stage D1) was unclear in the telson and did not occur synchronically in different appendices. The duration of successive moulting stages within each larval instar and major morphological changes in the telson are summarized in Table 1. The knowledge of this sequence can be used as a tool for the evaluation of the developmental state within larval stages, which may facilitate future studies on crab aquaculture.