GEOquery is a software tool that connects the Gene Expression Omnibus (GEO) database with the BioConductor project, enabling users to access and analyze gene expression data from GEO directly within BioConductor. The GEO database contains nearly 140,000 gene expression experiments across a wide range of organisms, tissues, and conditions. BioConductor is an open-source project for analyzing genomic data using R. GEOquery simplifies the process of accessing and parsing GEO data, eliminating previous formatting and parsing challenges. It provides a bridge between GEO and BioConductor, allowing users to perform new analyses using advanced statistical and bioinformatic tools. GEOquery includes classes for various GEO entities, such as GDS (dataset), GPL (platform), GSM (sample), and GSE (series), each with associated methods for data retrieval and manipulation. The tool can convert GEO data into BioConductor data structures like ExpressionSet and MAList, facilitating integration with existing BioConductor tools. GEOquery enables efficient analysis and meta-analysis of microarray data, improving the ability to draw biologically meaningful conclusions from published genomic data. The software is available as part of the BioConductor project and is designed to be user-friendly, with a simple command (getGEO) for downloading and parsing data. The tool maintains all information from GEO records, providing a comprehensive and structured way to access and analyze gene expression data.GEOquery is a software tool that connects the Gene Expression Omnibus (GEO) database with the BioConductor project, enabling users to access and analyze gene expression data from GEO directly within BioConductor. The GEO database contains nearly 140,000 gene expression experiments across a wide range of organisms, tissues, and conditions. BioConductor is an open-source project for analyzing genomic data using R. GEOquery simplifies the process of accessing and parsing GEO data, eliminating previous formatting and parsing challenges. It provides a bridge between GEO and BioConductor, allowing users to perform new analyses using advanced statistical and bioinformatic tools. GEOquery includes classes for various GEO entities, such as GDS (dataset), GPL (platform), GSM (sample), and GSE (series), each with associated methods for data retrieval and manipulation. The tool can convert GEO data into BioConductor data structures like ExpressionSet and MAList, facilitating integration with existing BioConductor tools. GEOquery enables efficient analysis and meta-analysis of microarray data, improving the ability to draw biologically meaningful conclusions from published genomic data. The software is available as part of the BioConductor project and is designed to be user-friendly, with a simple command (getGEO) for downloading and parsing data. The tool maintains all information from GEO records, providing a comprehensive and structured way to access and analyze gene expression data.