UAAP Season 66 refers to the 66th season of the University Athletic Association of the Philippines (UAAP), the premier athletic league for collegiate institutions in the Philippines. It covered the academic year 2003-2004. The season officially opened on July 12, 2003, and was hosted by De La Salle University (DLSU). The theme for the season was "Reaching Greater Heights."
Eight member universities participated in various sports across different divisions (seniors, juniors, and women's). Key events and champions for the seniors division included:
- Men's Basketball: The Far Eastern University (FEU) Tamaraws claimed the championship, defeating the De La Salle University (DLSU) Green Archers in the finals.
- Women's Basketball: The De La Salle University (DLSU) Lady Archers secured the title.
- Men's Volleyball: The University of Santo Tomas (UST) Growling Tigers emerged as champions.
- Women's Volleyball: The De La Salle University (DLSU) Lady Spikers won the championship.
The season concluded with De La Salle University (DLSU) being awarded the General Championship for the seniors division, signifying their overall athletic excellence across all sports for the academic year.