A penicillin composition in dosage form for oral administration is produced by admixing penicillin with a neutral or mildly alkaline non-toxic compound compatible therewith which fails to evolve carbon dioxide upon acidification, the compound being present in an amount sufficient to protect a substantial portion of the penicillin against destruction by gastric hydrochloric acid.  Preferably the amount of the non-toxic compound is such as to produce a pH between 3.0 and 7.5 when reacted with the gastric hydrochloric acid.  Specified compounds are: di- and tri-sodium, di- and tri-potassium and magnesium citrates; disodium, dipotassium and calcium hydrogen phosphates; disodium, dipotassium and magnesium tartrates; disodium and magnesium malonates; disodium, dipotassium and magnesium malleates; sodium and magnesium acetates; sodium, dipotassium, magnesium and calcium lactates; sodium nicotinate; sodium and potassium salicylates; disodium dipotassium and magnesium succinates; sodium and potassium acetyl-salicylates; disodium, dipotassium and magnesium fumarates; disodium and dipotassium saccharates; sodium, potassium, magnesium and calcium gluconates; alumina and aluminium hydroxide.  The penicillin composition may be made up as powder or as a pill, tablet or capsule, either alone or compounded with diluents or excipients, e.g. lactose or the penicillin and the non-toxic compound may be packaged separately and be mixed just prior to use.  The Specification as open to inspection under Sect. 91 describes also the use of calcium phosphate as the non-toxic compound, and starch and sucrose as excipients.  This subject-matter does not appear in the Specification as accepted.ALSO:A penicillin composition in dosage form for oral administration is produced by admixing penicillin with a neutral or mildly alkaline non-toxic compound compatible therewith which fails to evolve carbon dioxide upon acidification, the compound being present in an amount sufficient to protect a substantial portion of the penicillin against destruction by gastric hydrochloric acid.  Preferably the amount of the non-toxic compound is such as to produce a pH between 3.0 and 7.5 when reacted with the gastric hydrochloric acid.  Specified compounds are:-di- and tri-sodium, di- and tri-potassium and magnesium citrates; disodium, dipotassium and calcium hydrogen phosphates; disodium, dipotassium and magnesium tartrates; disodium and magnesium malonates; disodium, dipotassium and magnesium maleates; sodium and magnesium acetates; sodium, dipotassium, magnesium and calcium lactates; sodium nicotinate; sodium and potassium salicylates; disodium, dipotassium and magnesium succinates; sodium and potassium acetylsalicylates; disodium, dipotassium and magnesium fumarates; disodium and dipotassium saccharates; sodium, potassium, magnesium and calcium gluconates; alumina and aluminium hydroxide.  The penicillin composition may be made up as powder or as a pill, tablet, or capsule, either alone or compounded with diluents or excipients, e.g. lactose; or the penicillin and the non-toxic compound may be packaged separately and be mixed just prior to use.  The Specification as open to inspection under Sect. 91 describes also the use of calcium phosphate as the non-toxic compound, and starch and sucrose as excipients.  This subject-matter does not appear in the Specification as accepted.