This article describes the new meta-analysis command metaan, which can be used to perform fixed- or random-effects meta-analysis. Besides the standard DerSimonian and Laird approach, metaan offers a wide choice of available models: maximum likelihood, profile likelihood, restricted maximum likelihood, and a permutation model. The command reports a variety of heterogeneity measures, including Cochran's Q, I2, H2M, and the between-studies variance estimate [Formula: see text]. A forest plot and a graph of the maximum likelihood function can also be generated.