St. Mary's High School, Quetta, is a high school located in Quetta, the capital of the Balochistan province of Pakistan.

The school conducts classes from playgroup to class 10 (Secondary School Certificate of the Board of Intermediate and Secondary Education, Balochistan). The medium of instruction is English.

The school's present site is in the cantonment of Quetta and came under military jurisdictions. The nearby church building was built before 1935 and survived the 1935 Quetta earthquake which destroyed more than half of the city.