Simulated acid rain(SAR) treatment caused a lethal effect on the newly germinated seedlings of Capsicum annum cv. Komyung even though the germination rate of the seeds was stimulated by the treatment of SAR. Young germinated seedlings were much more sensitive to SAR than the already-grown seedlings. The typical symptom caused by SAR was white spot or lesion on the leaf and appeared readily and severely at the low pH of SAR. Generally, Phytophthora rot was severer in SAR treatments than in control. However, the disease was less severe in lower pH of the SAR treatment than in higher pH. Pathogen inoculation following the SAR treatment increased the disease. The severest Phytophthora rot was observed in the SAR treatment of pH 4.0 or 4.5 regardless of the inoculation time.