Finally dug out the notes I made for passing peaks to nlinLS for fitting. I did indeed encounter the initial linewidth guess problem also, and I got around it by inserting a guess as described. The bit about adding a TROUBLE column to the outputed peaks should be obsolete now as Wim added this at the time at my request. Any code is 2006 vintage, so it almost certainly needs data model bit checking before use. To do the fitting really well, it would be nice to take processing into acount also in nlinLS. I posted to the nmpipe mailing list on this http://tech.groups.yahoo.com/group/nmrpipe/message/1256 but never did get any replies - if anyone has any insight into this I would love to hear it. -- Dr. Brian O. Smith ---------------------- B Smith at bio gla ac uk Division of Biochemistry & Molecular Biology, Institute Biomedical & Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK. Tel: 0141 330 5167/6459/3089 Fax: 0141 330 8640