Required Equipment for Brazilian Jiu-Jitsu Training
One of the nice things about training in Brazilian Jiu-Jitsu is that you don't need to spend a small fortune on equipment and training gear.  Nonetheless, a few items will be necessary to ensure your safety and comfort while training.
Starting Out
If you're brand new to Brazilian Jiu-Jitsu training, all you need to wear are some comfortable workout clothes.  A t-shirt and a pair of shorts will be fine for your first few classes.  Avoid anything too loose; baggy clothing can sometimes get caught while you're training.
No-Gi Classes
Half the classes each semester will focus on training without the traditional Jiu-Jitsu uniform, (commonly referred to by the Japanese terms gi or kimono).  For these classes, you will need the following items which can be purchased at nearly all sporting goods stores, department stores, or online:
T-Shirt or Rashguard: A t-shirt that's not too loose is fine, but most BJJ practitioners find they prefer to wear a compression shirt (also known as a rashguard).  Rashguards are form-fitting and wick moisture from your body.
Shorts or Gi Pants: Board shorts or fight shorts are the most preferable for no-gi training, although the pants from a martial arts gi may also be worn.  Some women prefer to wear compression shorts or full spandex leggings.
Gi Classes
Half the classes each semester will focus on training with the traditional Jiu-Jitsu Uniform, (commonly referred to by the Japanese terms Gi or Kimono).  For these classes, you will need the following:
BJJ Gi: Brazilian Jiu-Jitsu with the kimono places significant emphasis on grasping the cloth of your training partner's uniform, so durability is a factor.  If you have a gi from another martial art, you're welcome to bring it along to start, but unless it's a Judo gi, chances are good you'll need something stronger before long.
Both BJJ and Judo gi are made in a variety of weaves and thicknesses and are designed to withstand the rigors of these sports.  There is a growing variety of gi types available for purchase at a range of prices.  Starting out in Jiu-Jitsu, it's recommended that you get something well-made, but not exceptionally expensive.  White or blue gi are the most traditional colors and the best to start with.
Below are some of our favorite brands of BJJ Gi.  Fuji is the cheapest of the bunch and a good value for a starter gi.  Koral and Atama are at the other end of the spectrum.  You can also get fairly cheap judo gi at a number of sites on the internet, although they will be cut a bit differently than BJJ kimono.  Whatever you buy, consider trying on a friend's first to get an idea of what size will work best for you:
BJJHQ: a daily sale site that has regular deals on Jiu-Jitsu Gis and other gear.
MMAHQ: a daily sale site that has regular deals on No-Gi gear.
*Please note that not all BJJ kimono come with white belts, so you might have to acquire them separately.
Recommended and Optional Equipment
The following equipment is optional, yet encouraged:
Jockstrap with Cup: One of the most important additional items.  Even though there is no striking in competitive Brazilian Jiu-Jitsu, accidents happen and it's best to be prepared.  Not all BJJ practitioners opt to wear jockstraps, but we encourage it.  Tighter-fitting is preferred here in order to prevent much shifting while training.
Mouthguard: Another important option, for the same reasons as listed above.  There are a number of styles available for a range of prices.  Be sure to follow the instructions closely when fitting for your mouth.
Protective Earwear: A small percentage of BJJ practitioners find that the friction inherent to the sport can cause pain and eventual swelling to their ears.  For most people, this won't be a problem; but for anyone with sensitive ears, we recommend headgear specific for grapplers.  If you start feeling pain in your ears, speak with an instructor to see if headgear might be the right option for you.

A guide to BJJ gear, written by Andrius Schmid. 08/2011.