Four new chromenones, kielmeyerones A-D (1-4), were obtained from the roots of Kielmeyera reticulata. Their structures were elucidated based on spectroscopic data (NMR and HRESIMS) interpretation. The pharmacological activity of kielmeyerone A (1), the major compound, was evaluated using in vitro and in vivo inflammation and pain models. During in vitro screening, 1, at noncytotoxic concentrations (0.097-1.56 μM), inhibited NO production by J774 macrophages stimulated with LPS and IFN-γ. In the complete Freund's adjuvant-induced inflammation model in mice, 1 (12.5-50 mg/kg) inhibited paw edema, demonstrating an anti-inflammatory effect. Additionally, 1 (12.5-50 mg/kg) induced a dose-dependent antinociceptive effect in the late phase of the formalin test, a profile similar to those of nonsteroidal anti-inflammatory drugs. Mice treated with 1 (100 mg/kg) did not show motor performance alterations using a rota-rod test. Thus, the present study has characterized new chromenones from Kielmeyera reticulata and has provided evidence of the anti-inflammatory and antinociceptive properties of one of these, kielmeyerone A (1).