In order to determine the hepatotoxicity of rifampicin in children treated for tuberculosis, a survey was performed of 18 children receiving this medicine in combination with isoniazid. Fifteen of the 18 children (83%) showed a rise in ASAT values and 11 (61%) in ALAT values exceeding 29U/L. Seven children with maximal ASAT values between 40 and 100 U/L were treated without any changes in the regimen and the transaminases normalized later in the treatment. Six out of the eight children with ASAT values over 100 U/L were allowed a three-week pause in their therapy, one was given the same dose of rifampicin, and in one the treatment was discontinued entirely. The therapy was discontinued in an additional three children because of a second high rise in the transaminase values. Liver injury can occur at any time during treatment, and thus makes continuous follow-up tests necessary.