In the case of a lack of conformity of the delivered goods with the condition of the goods owed in the contract of sale, the purchaser is entitled to supplementary performance by subsequent repair or replacement by the seller. This claim to supplementary performance modifies the contractual requirements of performance, while at the same time suspending the buyer's other warranty remedies, which in principle presuppose the unsuccessful expiry of a time limit set for the supplementary performance and thus turn into remedies which have lower priority. Taking into account EU legal standards in the Directive 1999/44/EC and the regulations of the UN Convention on Contracts for the International Sale of Goods /CISG), Frank Skamel describes the scope of the statutory alternatives of supplementary performance, examines their content in relation to the contractual claim for primary specific performance and differentiates between them and compensatory damages.