It has been commonly reported by teachers and learners the strong and positive relationship between lexis and reading comprehension. This claim has been usually grounded on experience. In consequence, this paper attempts to find research-based evidence to support the connection between lexis and reading comprehension. To do this, a review of 128 studies was conducted using a set of criteria, after which thirteen studies were selected and screened to look for specific patterns. Salient themes emerged from the analysis: lexical coverage, direct instruction, lexical knowledge (breadth and depth), incidental and intentional learning and receptive and productive lexical knowledge. The analysis supports the connection between lexis and reading comprehension not only in EFL, but also in ESL and L1 contexts. In line with it, the research suggests that teachers should focus on systematic lexis instruction since it aids learners to increase both lexical knowledge and reading comprehension gains.