To determine alterations in Th2 chemokines eotaxin and monocyte chemoattractant protein-4 (MCP-4), and cytokines interleukin-5 (IL-5) and interleukin-13 (IL-13), in nasal polyps (NP) after steroid treatment. Cytokine/chemokine levels were measured in NP before and after steroid therapy and compared to control sinus mucosa. Twenty-one patients (control = 7, NP = 14) were enrolled. Eotaxin and MCP-4 were significantly higher than control tissue (P = 0.004 and 0.003). All four mediators decreased after steroid treatment (P < 0.03). IL-5 and IL-13 in untreated polyps were not significantly different from controls. Patients showed clinical improvement according to SNOT-20 scores (average presteroid score 19, poststeroid score 13) and endoscopic grading (1.75 each side presteroid, 1.13 poststeroid). Steroids significantly decreased all cytokine/chemokine levels, but the impact on Th2 chemokines was of a much greater magnitude. Novel approaches to block inflammatory mediators, particularly Th2 chemokines, may lead to better control of nasal polyposis in the future.