Rape Crisis Scotland (RCS) said it received 3957 contacts from people looking for support and information during 2012/13, compared to 2712 in the previous year.
That 45.9% increase has been attributed to several factors, including the introduction of their email support service, which received and responded to 441 emails last year.
Police recorded 1109 indecent and sexual assaults last year - an increase of 31.5% since 2006/07 when 843 were recorded and a rise of almost 5% from 2011/12.
RCS helpline manager and national coordinator Sandie Barton said the organisation had expanded the ways survivors of sex crimes could get in touch with them.
She said: "It's an indication of how busy we are. Email is a growing part of our service and it's often more suitable for people to email than phone.
"Sometimes it's used by people who have been raped abroad and they need that information there and then.
"Maybe they're not ready to phone and a few emails are passed between the survivor and one of our workers and then they visit one of our centres or phone.
"We've also widened access to different groups of survivors and we are continuing to work on that."
RCS has also been working with Deaf Connections and Wise Women on access for people with hearing difficulties.