Police were called in to control the throngs in Bangladesh amid fears of a stampede that could crush the boy, named Kiron, and his 22-year-old mother.
The baby seems healthy but last night doctors were trying to confirm how many sets of vital organs he has and assess his chances of survival.
Police were called in to control the masses as the baby was moved from one hospital to another for security reasons.
Officials feared that unless the baby was moved from the clinic in Bangladesh, where he was born, to a more secure hospital, the crowd would force their way in to gaze at the amazing sight.
If that happened, it was feared, mother and baby would be crushed.
In the past babies born with physical abnormalities have been viewed in countries such as Bangladesh and India as living gods.
Last night the boy, named Kiron, was under police protection as doctors tried to determine whether he had any future.
Kiron was born in a cesarean operation on Monday, weighing just over 12lb, in Keshobpur, 100 miles from the capital, Dhaka.
'He has one stomach and he is eating normally with his two mouths,' said gynaecologist Mohamad Abdul Bari.
'He has one genital organ and a full set of limbs.'
Dr Bari said the baby developed from one embryo 'but there was a developmental anomaly'.
He said the clinic had been unable to determine whether the baby had one or two sets of vital organs.
But while his life was not in immediate danger, it had been necessary for him and his 22-year-old mother to be moved to a larger hospital in nearby Jessore city because of the growing crowd outside the clinic.
'Even before we moved the baby and his mother from the clinic the crowd had grown to 150,000 and it is now just as big at the hospital.
'We fear the crowds are going to grow even bigger as word spreads.
'People are desperate to have a look at this baby.
'We had to call the police to control the situation at the clinic and now the police are on 24-hour guard at the hospital.'