"Deep Inside" is a song by American R&B singer-songwriter Mary J. Blige. It was third single released in the United Kingdom from her fifth album, Mary, and the second single from the album in the United States. Like the preceding single, "All That I Can Say", it was a moderate success in the United States peaking at number fifty-one on the Billboard Hot 100, seven places lower than the previous single. In the United Kingdom, however, it was one of her least successful singles to date and Blige's first single to miss the UK top 40 since the first release of "Real Love" seven years earlier.