Bristol city Council has failed to meet its target for reducing the number of looked-after children who miss school for 25 days or more.
But the percentage figure fell slightly, to 15.7 per cent, between October 2007 and September 2008.
The number of children looked after by the authority rose by 22 to 482 between 2007 and 2008.
GCSE results were the best since the council started recording the progress of children in care.
Among the 60 children in care who took GCSEs, many missed the five A*-to-C outcome by one grade. Just under 40 per cent of them had a statement of special educational needs.
The number of looked-after Year 11 pupils who were in training or jobs or staying on at school rose slightly, by 3.8 per cent to 80.7 per cent.
Teacher assessments of looked-after children found improvements in reading and writing at key stage 1, and in maths and science at KS2, but a slight drop in English.
The same trend was seen in KS3 results, but only half of children in care sat all three tests.
This year, 12 volunteers in 13 schools will help 41 looked-after children with reading and writing.
Karen Gazzard, council leader for corporate parenting, said: "Children in care's attendance at school is beneath target, but is slowly improving."