The Genotype-Tissue Expression (GTEx) project aims to characterize gene expression levels across individuals and diverse human tissues, focusing on the impact of genetic variation on gene regulation. This study reports on the GTEx v6p release, which includes data from 449 donors across 44 tissues, enabling the analysis of tissue-specific gene expression and genetic associations with gene expression levels (eQTLs). The analysis identifies pervasive cis-eQTLs affecting the majority of genes and trans-eQTLs in 18 tissues, with increased tissue specificity compared to cis-eQTLs. The study evaluates the functional characteristics, genomic context, and relationship to disease-associated variation of both cis- and trans-eQTLs. It also demonstrates that multi-tissue, multi-individual data can be used to identify genes and pathways affected by human disease-associated variation, providing insights into gene regulation and the genetic basis of diseases. The GTEx project's comprehensive resource has already contributed to the identification of tissue-specific regulatory effects underlying variants associated with human diseases. Future plans include increasing sample size and integrating complementary molecular data to further enhance the understanding of gene regulatory mechanisms and their contributions to human traits and diseases.The Genotype-Tissue Expression (GTEx) project aims to characterize gene expression levels across individuals and diverse human tissues, focusing on the impact of genetic variation on gene regulation. This study reports on the GTEx v6p release, which includes data from 449 donors across 44 tissues, enabling the analysis of tissue-specific gene expression and genetic associations with gene expression levels (eQTLs). The analysis identifies pervasive cis-eQTLs affecting the majority of genes and trans-eQTLs in 18 tissues, with increased tissue specificity compared to cis-eQTLs. The study evaluates the functional characteristics, genomic context, and relationship to disease-associated variation of both cis- and trans-eQTLs. It also demonstrates that multi-tissue, multi-individual data can be used to identify genes and pathways affected by human disease-associated variation, providing insights into gene regulation and the genetic basis of diseases. The GTEx project's comprehensive resource has already contributed to the identification of tissue-specific regulatory effects underlying variants associated with human diseases. Future plans include increasing sample size and integrating complementary molecular data to further enhance the understanding of gene regulatory mechanisms and their contributions to human traits and diseases.