The international study, external records the knowledge and skills of more than 760,000 15-year-olds from 91 countries and is co-ordinated by the Organisation for Economic Co-operation and Development (OECD).
Scotland has taken part in every cycle of the study since 2000 – with 115 schools and colleges, and 3,066 pupils across the country taking part in Pisa 2025.
The latest rankings show performance in Scotland’s high schools has improved in science but slipped in maths and reading since the 2022 study.
The Scottish government said the changes in results between the two studies were not statistically significant.
Scotland’s score in the 2025 Pisa assessment for reading was 488.
This is down from 493 in the 2022 assessment, and also a drop from 504 in 2018 and 526 in 2000 – when the Pisa study started.
The reading performance was above the average across all OECD countries – except Costa Rica, Luxembourg and Spain – of 463 points.
Scotland’s reading score is ahead of Wales (459) and Northern Ireland (482) but behind England (497), which saw its performance improve since the last study.
For maths, the score in Scotland was 467, down from 471 in 2022 and just above the OECD average of 465 points.
The latest score for maths continues the trend of worsening performance in Scotland as the score in 2018 was 489 and in 2015 it was 491.
Compared with other UK nations, Scotland is behind Northern Ireland (473) and England (492), but ahead of Wales (456).