Most visitors don’t need a visa to enter the Ukraine, including those from the USA, Canada, or EU citizens for stays up to 90 days. The Ukraine MFA website (http://www.mfa.gov.ua/mfa/en/509.htm) lists nationalities that require a visa.
Health and Safety
Ukrainian health and hygiene standards fall behind the US and much of Europe and there are risks. Avoid drinking the tap water as most pipes are lead. You can brush your teeth with tap water, but be sure to run the tap for a few seconds. Food standards are lax, so try to stay away from street food (especially salads with mayonnaise), and make sure the meat is thoroughly cooked and piping hot.
HIV/AIDS is a problem in the Ukraine, while state-run hospitals are lacking in facilities. If you have to, use the private ones, such as the American Medical Center (+380-44-490-7600) in Kiev. Having travel insurance for any potential incident is a must as these are not cheap. There are no specific vaccinations to have before a visit, but keeping up to date with tetanus boosters is recommended.
Most city streets are fine to walk around by day, though there are dodgy areas and drunks are ubiquitous on Fridays and Saturday. Andrew’s Descent in Kiev should be avoided late at night. Anti-Semitism and racism (toward blacks) is well documented. Stay vigilant, use notable government approved currency exchanges, be aware that credit card fraud is a problem, and that pickpockets are rife on the Kiev Metro and stations to avoid a situation that would ruin the trip.