The rain held off, but clouds gathered overhead and the breeze was cold.
While official crowd numbers were not finalised, organisers expected something close to last year's attendance of more than
106,000.
The crowd swarmed the betting windows and bars and brought some areas to a standstill.
Flemington's lawns were packed with punters, some in sensible hats, shawls and jackets, while others had dressed for warmer weather.
Tony Giddins, 40, from Shepparton in Victoria, said it was his
20th Melbourne Cup, and not his first in a dress.
Wearing a black cocktail frock over his hairy, tattooed chest, Mr Giddins finished his outfit with baby-pink gloves and matching handbag.
"The wife, she's wearing a black suit and my mate's wandering around in a nappy with a bottle of Bundy (rum)," he said.
Mr Giddins said going to the races in drag was the best way to meet women.
"That Jennifer Hawkins, she came up to me with one of my mates and she asked me for a photo. I couldn't believe it!" he said.
But he admitted the outfit was not practical, complaining: "My nipples are freezing."
Worse, it might even prevent him placing a bet.
"I can't get to the betting ring," he said.
"Every time I make a move, some bloke pulls my dress up."
Irish fans turned out in their country's colours, some draped in their flag in support of strong cup chance, Yeats.
Less common but also visible were women in kimonos.
Two Japanese horses were among this afternoon's field - Delta Blues and Pop Rock, who proved popular in the bookies' ring.
Meanwhile the federal government has announced the Flemington course will be added to the National Heritage List.
The track held its first Melbourne Cup in 1861.