A composition includes particles including at least about 95 wt % of amphotericin B, wherein the particles have a mass median diameter ranging from about 1.1 .mu.m to about 1.9 .mu.m. Another composition also includes particles including at least about 95 wt % of amphotericin B, wherein at least about 80 wt % of the particles have a geometric diameter ranging from about 1.1 .mu.m to about 1.9 .mu.m. Yet another composition includes particles including amphotericin B, wherein the particles have a mass median diameter less than about 1.9 .mu.m, and wherein the amphotericin B has a crystallinity level of at least about 20%. Unit dosage forms, delivery systems, and methods may involve similar compositions.