A method for detecting an analyte in a sample, comprising: (a) contacting said sample with at least one set of at least first and second proximity probes, which probes each comprise an analyte-binding domain and a nucleic acid domain and can simultaneously bind to the analyte; (b) allowing the nucleic acid domains of the proximity probes to interact with each other upon binding of said proximity probes to said analyte, wherein said interaction comprises the formation of a duplex; (c) contacting said sample with a component comprising 3' exonuclease activity, wherein said component comprising 3' exonuclease activity is selected from a nucleic acid polymerase having 3' exonuclease activity and exonuclease I, and wherein said component is able to degrade nucleic acid domains which have not interacted to form a duplex and which have a free and unprotected 3' end; (d) extending the 3' end of at least one nucleic acid domain of said duplex to generate an extension product, wherein the step may occur contemporaneously with or after step (c); and (e) amplifying and detecting the extension product; wherein for the amplification of step (e) a reagent is added to the sample, optionally together with a polymerase and dNTPs for amplification of the extension product, wherein the reagent is selected from the list consisting of: (i) a primer for PCR amplification; (ii) a padlock probe or circular oligonucleotide comprising a sequence which is complementary to the extended part of the extension product; and (iii) an oligonucleotide which acts as a ligation template for circularisation of an oligonucleotide comprising the extended part of the extension product; and is added to the sample before, at the same time or after the contacting step (c). (a) contacting said sample with at least one set of at least first and second proximity probes, which probes each comprise an analyte-binding domain and a nucleic acid domain and can simultaneously bind to the analyte; (b) allowing the nucleic acid domains of the proximity probes to interact with each other upon binding of said proximity probes to said analyte, wherein said interaction comprises the formation of a duplex; (c) contacting said sample with a component comprising 3' exonuclease activity, wherein said component comprising 3' exonuclease activity is selected from a nucleic acid polymerase having 3' exonuclease activity and exonuclease I, and wherein said component is able to degrade nucleic acid domains which have not interacted to form a duplex and which have a free and unprotected 3' end; (d) extending the 3' end of at least one nucleic acid domain of said duplex to generate an extension product, wherein the step may occur contemporaneously with or after step (c); and (e) amplifying and detecting the extension product; wherein for the amplification of step (e) a reagent is added to the sample, optionally together with a polymerase and dNTPs for amplification of the extension product, wherein the reagent is selected from the list consisting of: (i) a primer for PCR amplification; (ii) a padlock probe or circular oligonucleotide comprising a sequence which is complementary to the extended part of the extension product; and (iii) an oligonucleotide which acts as a ligation template for circularisation of an oligonucleotide comprising the extended part of the extension product; and is added to the sample before, at the same time or after the contacting step (c). (i) a primer for PCR amplification; (ii) a padlock probe or circular oligonucleotide comprising a sequence which is complementary to the extended part of the extension product; and (iii) an oligonucleotide which acts as a ligation template for circularisation of an oligonucleotide comprising the extended part of the extension product;