The research, by Sapient Interactive, revealed that 41% of marketers cited "lack of understanding" as the chief barrier to investment in social media.
No clear measurement or return on investment was stated by 19%, and the fact that social networking is still in an experimentation phase and not proven yet was raised by 17%.
Other issues raised regarded markerters who did not know where to start ("there's too much out there"), cited by 14% of those surveyed.
The reservations come in contrast to the 50% who responded saying that 2009 will be the year of social networking for marketers.
The survey also showed that in the past six months, 54% of respondents had run a social networking campaign.
However, of these campaigns, 63% were as part of a wider marketing campaign rather than a standalone, possibly highlighting the cautious approach that UK marketers are taking to social networking.
Nigel Vaz, vice president and head of Sapient Interactive Europe, said: "Social networks should be a marketer's dream.
"The time spent on social networking sites is increasing, and the audience has broadened and matured, therefore providing the ideal platform for carefully targeted, creative and personalised marketing campaigns.
"However, there is still a lot of confusion about how marketers embrace social networking either as campaigns on their own or as part of wider marketing campaigns.
"We believe it is about creating the social experiences that personify your brand. Segmentation and content are key because if doesn't resonate, it fails."
The survey also showed that only 9% of respondents think that "social networking is overrated".
The most used social media by marketers are:
- Sites like YouTube and Flickr (62%)
- Micro-blogs such as Twitter (59.8%)
- Corporate/campaign blogs (59%)