This directory first contains errata and addenda for the book "A Course in Computational Algebraic Number Theory" by Henri Cohen Graduate Texts in Mathematics 138, Springer-Verlag ISBN 3-540-55640-0 Springer-Verlag Berlin Heidelberg New York ISBN 0-387-55640-0 Springer-Verlag New York Berlin Heidelberg First Printing 1993, XXI + 534 pages. Second Corrected Printing 1995, XXII + 534 pages. Third Corrected Printing 1996, XX + 545 pages. Fourth Corrected Printing 2000, XX + 545 pages (identical to the third). You can get the AmsTeX 2.0 or later files errataxxx.tex, the dvi files errataxxx.dvi or the gzipped Postscript files errataxxx.ps.gz errata2all.tex: contains the list of errata and addenda to the first printing. Some of the addenda have not been included in the second printing for lack of space. errata3.tex: contains the list of errata and addenda to the second printing (published in December 1994, dated 1995). errata4.tex: contains the list of errata and addenda to the third and fourth printings (published in November 1996 and early 2000). It also contains errata and addenda for the book "Advanced Topics in Computational Number Theory" by Henri Cohen Graduate Texts in Mathematics 193, Springer-Verlag ISBN 0-387-98727-4 Springer-Verlag New York Berlin Heidelberg First Printing 2000, XV + 578 pages. errataadv1.tex: contains the list of errata and addenda to the first printing (published in January 2000).