SUMMARY: Human single nucleotide polymorphism (SNP) chips which are used in genome-wide association studies (GWAS) permit the genotyping of up to 4 million SNPs simultaneously. To date, about 1000 human SNPs have been identified as statistically significantly associated with a disease or another trait of interest. The identified SNP is not necessarily the causal variant, but it is rather in linkage disequilibrium (LD) with it. CandiSNPer is a software tool that determines the LD region around a significant SNP from a GWAS. It provides a list with functional annotation and LD values for the SNPs found in the LD region. This list contains not only the SNPs for which genotyping data are available, but all SNPs with rs-IDs, thus increasing the likelihood to include the causal variant. Furthermore, plots showing the LD values are generated. CandiSNPer facilitates the preselection of candidate SNPs for causal variants. AVAILABILITY AND IMPLEMENTATION: The CandiSNPer server is freely available at http://www2.hu-berlin.de/wikizbnutztier/software/CandiSNPer. The source code is available to academic users 'as is' upon request. The web site is implemented in Perl and R and runs on an Apache server. The Ensembl database is queried for SNP data via Perl APIs.