The sultry siren looked stunning in her revealing outfit on her way back from Venice Film Festival where she attended the screening of her new film Machete.
Alba, 29, wore faded roll-up jeans, cream cropped jacket and a beige see-through top which showed her black bra underneath.
Peek-a-boo: Jessica Alba wore a sheer top through LAX airport revealing her bra and a hint of her toned stomach
The Fantastic Four star does try to be modest sometimes by revealing that she didn't go totally naked when filming nude scenes in Machete.
'I had undies on, and I had other stuff on, and they just sort of etched it out in post production. That's not really me. I'm better covered up.'
Jessica recently stood up for her Machete co-star Lindsay Lohan saying that despite LiLo's recent troubles she's a 'brilliant actress'.
Tease: Alba covered up half of her top as faced the waiting photographers. She was on her way back from Venice Film Festival promoting her new movie Machete
'The fact that she can poke fun at herself - she's a brilliant actress. Mean Girls is a classic. It's so good. How can you ever forget that?
'I think people should probably focus more on someone's career and maybe less on someone's personal circumstances.
'It's nobody's business. Everyone goes through their own thing.'
Jessica is back to work in earnest after taking time out to have her baby Honor who is now two-years-old.
Why so glum? Alba looks a bit tired after her long flight from Italy but has husband Cash Warren and two-year-old daughter Honor waiting for her at home
She's also appearing in the star-studded cast of Little Fockers, the third instalment in the franchise that features Ben Stiller and Robert De Niro playing out the awkward son-in-law vs. overprotective father-in-law relationship.
Jessica revealed that her character in the movie is 'totally crazy'.
'I play a pharmaceutical sales rep who is very, um, outgoing and has no sense of personal space. She says exactly what's on her mind and has no filter at all.
Back to work: After taking time out to have her daughter, Alba is back to work with new film Machete, pictured here at the opening of the movie at Venice Film Festival
'She was really fun to play because I'm pretty much the opposite of that.'
Alba admitted that keeping a straight face on set was a big challenge as most of her scenes were with funnyman Ben Stiller.
Little Fockers, which is set a few months after the events of the last instalment Meet The Fockers, is due in theatres December 22.