An ex vivo or in vitro method for carrying out an amplification of at least one target nucleotide sequence by a polymerase chain reaction, comprising the following steps: a) providing a first environment comprising at least one sample possibly containing said target nucleotide sequence; b) providing a second environment comprising a single control to ascertain the absence of contamination and the functioning of the reaction reagents, said single control containing a nucleotide sequence comprising: - an amplifiable nucleic acid having a different or partially different sequence from said target nucleotide sequence and - two hybridization sites for two primers, respectively at the 5 'and 3' ends of said amplifiable nucleic acid, and - a region inside the primer hybridization sites for the hybridization of a probe having a different sequence from said target nucleotide sequence, c) adding a mixture to said sample and to said single control comprising: - two primers capable of triggering the PCR reaction of the target nucleotide sequence; - two primers capable of triggering the PCR reaction of the single control; - a first specific probe for the target nucleotide sequence; - a second specific probe for the amplifiable sequence of the single control; - appropriate reagents; d) performing the PCR reaction on said mixture to obtain and detect copies of the target nucleotide sequence if present in said sample and copies of the nucleotide sequence of the single control, wherein the two primers capable of triggering the PCR reaction of the single control are also capable of triggering the PCR reaction of the nucleotide sequence of an exogenous target previously added to the sample of step a and wherein preferably in step c) the mixture further comprises a third specific probe for the nucleotide sequence of said exogenous target. a) providing a first environment comprising at least one sample possibly containing said target nucleotide sequence; b) providing a second environment comprising a single control to ascertain the absence of contamination and the functioning of the reaction reagents, said single control containing a nucleotide sequence comprising: - an amplifiable nucleic acid having a different or partially different sequence from said target nucleotide sequence and - two hybridization sites for two primers, respectively at the 5 'and 3' ends of said amplifiable nucleic acid, and - a region inside the primer hybridization sites for the hybridization of a probe having a different sequence from said target nucleotide sequence, - an amplifiable nucleic acid having a different or partially different sequence from said target nucleotide sequence and - two hybridization sites for two primers, respectively at the 5 'and 3' ends of said amplifiable nucleic acid, and - a region inside the primer hybridization sites for the hybridization of a probe having a different sequence from said target nucleotide sequence, c) adding a mixture to said sample and to said single control comprising: - two primers capable of triggering the PCR reaction of the target nucleotide sequence; - two primers capable of triggering the PCR reaction of the single control; - a first specific probe for the target nucleotide sequence; - a second specific probe for the amplifiable sequence of the single control; - appropriate reagents; - two primers capable of triggering the PCR reaction of the target nucleotide sequence; - two primers capable of triggering the PCR reaction of the single control; - a first specific probe for the target nucleotide sequence; - a second specific probe for the amplifiable sequence of the single control; - appropriate reagents; d) performing the PCR reaction on said mixture to obtain and detect copies of the target nucleotide sequence if present in said sample and copies of the nucleotide sequence of the single control, wherein the two primers capable of triggering the PCR reaction of the single control are also capable of triggering the PCR reaction of the nucleotide sequence of an exogenous target previously added to the sample of step a and wherein preferably in step c) the mixture further comprises a third specific probe for the nucleotide sequence of said exogenous target. wherein the two primers capable of triggering the PCR reaction of the single control are also capable of triggering the PCR reaction of the nucleotide sequence of an exogenous target previously added to the sample of step a and wherein preferably in step c) the mixture further comprises a third specific probe for the nucleotide sequence of said exogenous target.