What kinds of instruments are used in hip hop music?

It really depends. I mean most hip-hop is mixed a dubbed and played-back in a concert off a giant mixing board... but the new wave of artists really like having a percussion background (The Roots, Lupe Fiasco, Lil Wayne, Kanye) and a whole band to really improve the quality of their live performances. When recording it always sounds better to record a live band playing simple beats and then loop or mix them for the album. I find that the best hiphop music combines mixing and live playing (with as many different insturments as possible).

The drum beat is a core element of hip hop production. Its speed and complexity dictates the pace and impact of the recording. While some beats are sampled, others are created by drum machines such as the Roland TR-808 and the Alesis SR-16. Others yet are a hybrid of the two techniques, sampled parts of drum beats that are arranged in original patterns altogether. Another mainstay in hip-hop is the use of the Ensoniq ASR-10 synthesizer to provide beats, particularly by The Neptunes and the MPC 2000.

Since the percussive element of hip hop music is the very punctuation of its sound, the sounds a producer chooses to represent the percussion are important. Some producers have drum kits all their own, such as Dr. Dre, Timbaland, DJ Paul & Juicy J, Swizz Beatz and Neptunes. Some drum sounds, such as the TR-808 cowbell, remain as historical elements of hip hop lore used in modern hip hop to lend a more credible and mature sound to the recording.
all insturments are used in hip hop today,its come a long way