5. Black Mamba:

The feared Black Mamba is found throughout many parts of the African continent. They are known to be highly aggressive, and strike with deadly precision. They are also the fastest land snake in the world, capable of reaching speeds of up to 20km/h. These fearsome snakes can strike up to 12 times in a row. A single bite is capable of killing anywhere from 10-25 adults. The venom is a fast acting neurotoxin. Its bite delivers about 100–120 mg of venom, on average; however, it can deliver up to 400 mg. If the venom reaches a vein, 0.25 mg/kg is sufficient to kill a human in 50% of cases. The initial symptom of the bite is local pain in the bite area, although not as severe as snakes with hemotoxins. The victim then experiences a tingling sensation in the mouth and extremities, double vision, tunnel vision, severe confusion, fever, excessive salivation (including foaming of the mouth and nose) and pronounced ataxia (lack of muscle control). If the victim does not receive medical attention, symptoms rapidly progress to severe abdominal pain, nausea and vomiting, pallor, shock, nephrotoxicity, cardio toxicity and paralysis. Eventually, the victim experiences convulsions, respiratory arrest, coma and then death. Without antivenin, the mortality rate is nearly 100%, among the highest of all venomous snakes. Depending on the nature of the bite, death can result at any time between 15 minutes and 3 hours.

4. Taipan Snake:

Another entry from Australia, the venom in a Taipan is strong enough to kill up to 12,000 guinea pigs. The venom clots the victim’s blood, blocking arteries or veins. It is also highly neurotoxic. Before the advent of an antivenin, there are no known survivors of a Taipan bite, and death typically occurs within an hour. Even with successful administration of antivenin, most victims will have an extensive stay in intensive care. It has been likened to the African Black Mamba in morphology, ecology and behavior.

3. Blue Krait:

The Malayan or Blue Krait is, by far, the most deadly of this species. Found throughout South East Asia and Indonesia, 50% of bites from the deadly Blue Krait are fatal, even with the administration of antivenin. Kraits hunt and kill other snakes, even cannibalizing other Kraits. They are a nocturnal breed, and are more aggressive under the cover of darkness. However, overall they are quite timid and will often attempt to hide rather than fight. The venom is a neurotoxin, 16 times more potent than that of a Cobra. It quickly induces muscle paralysis by preventing the ability of nerve endings to properly release the chemical that sends the message to the next nerve. This is followed by a period of massive over excitation (cramps, tremors, spasms), which finally tails off to paralysis. Fortunately, bites from Kraits are rare due to their nocturnal nature. Before the development of antivenin, the fatality rate was a whopping 85%. Even if antivenin is administered in time, you are far from assured survival. Death usually occurs within 6-12 hours of a Krait bite. Even if patients make it to a hospital, permanent coma and even brain death from hypoxia may occur, given potentially long transport times to get medical care.

2. Eastern Brown Snake:

Don’t let the innocuous name of this snake fool you, 1/14,000 of an ounce of its venom is enough to kill an adult human. Coming in a variety of species, the Eastern Brown snake is the most venomous. Unfortunately, its preferred habitat is also along the major population centers of Australia. The Brown snake is fast moving, can be aggressive under certain circumstances and has been known to chase aggressors and repeatedly strike at them. Even juveniles can kill a human. The venom contains both neurotoxins and blood coagulants. Fortunately for humans, less than half of bites contain venom and they prefer not to bite if at all possible. They react only to movement, so stand very still if you ever encounter one in the wild. 

1. Fierce Snake or Inland Taipan:

While I did say that I would not include multiple sub-species in this list, the incredible Inland Taipan deserves a spot of its own. It has the most toxic venom of any land snake in the world. The maximum yield recorded for one bite is 110mg, enough to kill about 100 humans, or 250,000 mice! With an LD/50 of 0.03mg/kg, it is 10 times as venomous as the Mojave Rattlesnake, and 50 times more than the common Cobra. Fortunately, the Inland Taipan is not particularly aggressive and is rarely encountered by humans in the wild. No fatalities have ever been recorded, though it could potentially kill an adult human within 45 minutes.

also on the same number is 

1. Belcher’s Sea Snake:

The most venomous snake known in the world, a few milligrams is strong enough to kill 1000 people! Less than 1/4 of bites will contain venom, and they are relatively docile. Fisherman are usually the victims of these bites, as they encounter the species when they pull nets from the ocean. Found throughout waters off South East Asia and Northern Australia.

Source: http://listverse.com/2011/03/30/top-10-most-venomous-snakes/