<div><p>LEPA is one of the most conserved translation factors and is found from bacteria to higher plants. However, the physiological function of the chloroplast LEPA homolog in higher plants remains unknown. Herein, we demonstrate the physiological role of cpLEPA in enabling efficient photosynthesis in higher plants. The <em>cplepa-1</em> mutant displays slightly high chlorophyll fluorescence and pale green phenotypes under normal growth conditions. The growth of the <em>cplepa-1</em> mutant is reduced when grown on soil, and greater reduction is observed under intense light illumination. Photosynthetic activity is impaired in the <em>cplepa-1</em> mutants, which is reflected in the decreased steady-state levels of chloroplast proteins. <em>In vivo</em> protein labeling experiments explained the decrease in the steady-state levels of chloroplast proteins. An abnormal association of the chloroplast-encoded mRNAs with ribosomes suggests that the protein synthesis deficiencies in <em>cplepa-1</em> are due to defects in translation initiation in the chloroplasts. The cpLEPA protein appears to be an essential translation factor that promotes the efficiency of chloroplast protein synthesis.</p> </div