The orally bioavailable hydrochloride salt of the synthetic imidazothiazole derivative levamisole with anthelminthic and immunostimulating activities. In immunosuppressed states, levamisole may restore immune function by: 1) stimulating antibody formation, 2) stimulating T-cell activation and proliferation, 3) potentiatiating monocyte and macrophage phagocytosis and chemotaxis and 4) increasing neutrophil mobility, adherence, and chemotaxis.