Hydrogen-bond arrangements in acid and peracid-amides are discussed. The familiar acid dimer motif is observed for these acids and dimers are linked through amide-amide hydrogen-bonds to form ribbon or sheet networks. Peracid dimers are not observed and instead extensive networks are built up from peracid proton to amide carbonyl hydrogen-bonds and amide proton to peracid group hydrogen-bonds. This last interaction can be two-centred involving the peracid carbonyl, or three-centred involving the peracid cabonyl and terminal peroxy oxygen.