Olivia Wilde makes a chic appearance at a private Hollywood Hills party alongside boyfriend Caspar Jopling

Olivia Wilde made a chic appearance as she stepped out a private Hollywood Hill party alongside her boyfriend Caspar Jopling.

The American actress and filmmaker, 41, showed off her stunning figure on Thursday evening as she left the bash.

Olivia oozed glamour as she wore a dazzling Oscar de la Renta chevron-pattern silk twill dress.

She completed her look with a pair of black pointed high heels. 

Pictures show Olivia leaving the party, which she attended with her boyfriend Caspar Jopling.

It's understood the pair made a quiet entrance and slipped away later in the night.

As they waited for their car to arrive, Caspar could be seen in the background of one shot.

Other stars in attendance include mayoral hopeful, Nithya Raman and comedian Dave Chapelle.

Olivia has been rumored to be dating art dealer Caspar since they were spotted on a romantic stroll together in London last October.

The couple had their first official outing together when they attended W Magazine's New York Fashion Week party.

Just a week earlier, the couple spent three hours having a meal and drinking red wine at The Pelican restaurant in the West London enclave before their passionate embrace outside the venue.

Sources previously revealed Caspar, who split from singer Ellie Goulding, 39, after five years of marriage last year, is an investor in the restaurant and its nearby sister pub, The Fat Badger, allowing him to date Olivia in relative privacy.

The source told The Mail On Sunday: 'Those pubs have allowed Caspar to date a world-famous actress under the radar for months.

'They always manage to get the best tables - little concealed spots in dark corners reserved for celebrities.

'They tend to go to The Fat Badger for date nights because it's an invitation-only pub, with a secret smoking terrace upstairs.

'Caspar's friends think they are falling in love. Now they are ready to be open about their relationship so you can expect to see them out and about together more often.'

Olivia put herself in the firing line earlier this after becoming the latest in a growing line of celebrities to promote an MRI scan that is financially unattainable to the vast majority of ordinary working people. 

She shared a promotional post on behalf of Prenuvo, one of a growing number of health startups offering MRIs they say can detect cancer and other chronic diseases, years before symptoms even begin.

But with a hefty $2,500 price tag, the service - which is not covered by health insurance - is an indulgence only the privileged few can afford, prompting inevitable outrage across social media. 

Out-of-touch stars including Kim Kardashian, Rita Ora, Kate Hudson and British TV presenter Holly Willoughby have all faced heavy criticism for their willingness to promote the service - and even offering discount codes.

Perhaps with a degree of foresight, Wilde, 41, ensured her comments were switched off before promoting the service to Instagram followers.