If you're going on safari, you are likely to be with a tour group which will take care of you. Ignore the previous post, go and have fun.
I've not been on safari to Kenya, but I usually take the following"
1. Immodium AD, for the inevitable traveller's stomach
2. anti-mosquito patches (like quit-smoking patches). You can get them on the internet
3. Sunscreen and a hat
4. A does of cipro, in case you pick up a bug.
5. Swiss Army knife/leatherman
6. Small flashlight (maglight has best beam)
7. Rechargeable batteries, and appropriate charger (or converter) for the power source
8. Local SIM card for your mobile phone (if you have a GSM phone. If you don't have a GSM phone, you can buy a cheap one locally, and a prepaid card. Store emergency contact numbers, including US Embassy, in it before you go into the bush).
9. Extra memory cards for camera (assuming digital)
10. Sturdy, comfortable, broken in, waterproof hiking shoes
11. A waterproof case for your passport (and extra copies of your passport, left in lots of location, or also perhaps scanned and left with someone who can e-mail the scans back to you in case you lose your passport and need a replacement).
12. Gorp or other nibblies, in plastic bag.
13. Backpack.
The rest will really depend on the quality of the tour and the details (camping or hotel, etc). Sleeping bag, mosquito nets, etc may/not be needed.
Check also the immunization recommendations for Kenya. Hep vaccine, perhaps yellow fever, and (likely optional) malaria, cholera prevention may be recommended.
Don't forget to register your trip with the US EMbassy (
U.S. Department of State - Home Page look for travel registry link).
And Have Fun! I've always wanted to go on safari!