Twice failing admittance to the best Taipei high schools, Lee enrolled back home at Tanshui High. Boarding there, he was well known for going into the bathroom every night to study by its faint light. The dorm supervisor was so moved that he asked the school to keep the lights on at night in one classroom so students could study there.
在淡中住校期間，李登輝最有名的軼聞，大概就是每天晚上跑到廁所旁，借著微弱燈光苦讀，結果竟然感動了舍監，才特別要求校方晚上開放一間教室讓學生夜讀。