Myosin XVIII (MyoXVIII)1, the newest member of the myosin superfamily (1), consists of two subclasses MyoXVIIIA and MyoXVIIIB (1, 2). Myosin family members have a motor domain, one or more IQ motifs and c-terminal tails that usually form dimeric coiled-coils, each domain having critical roles in a variety of cell functions (1, 3). The MyoXVIIIA gene encodes short and long protein variants, the long variant having an N-terminal PDZ domain (4, 5). The long variant was discovered in mouse marrow stromal cells and has been designated as MysPDZα (4, 6) or more recently as MyoXVIIIAα (7) for the human gene. The short variant designated as MysPDZβ (4) or MyoXVIIIAβ(7) was first characterized in spleen (4), myeloid and other hematopoietic cells (5). MyoXVIIIA variants localize to different cellular compartments, but the functions of this myosin are not understood (6–9). Recently, we have discovered that variants of MyoXVIIIA mediate the function of surfactant protein A (SP-A) (10). SP-A is a member of the collectin family critical for innate immunity in the lung (11). Here we detail methods for bacterial expression of two recombinant domains of MyoXVIIIA.