Global metabolism of cancers exhibits a peculiar phenotype that is lactate acidosis (high lactate with acidic pH) in tumor microenvironment. Why tumor microenvironment becomes so responsive towards lactate is still not clear. In this review we have discussed lactate generation and recycling either exogenously, directly or indirectly by cancer cells via some transporters. Tumor cells in hypoxia use glucose rapidly and produce lactate while cells which have profuse oxygen supply take up lactate and use it for energy production which is referred as lactate shuttling between tumor cells. Escaping immune evasion which is also an emerging hallmark of cancer cells has also been discussed in this review with respect of lactate acidosis.