BackgroundDespite showing high rates of depression, university students prefer to seek assistance for their depression from informal sources, such as their friends, rather than seeking professional assistance. Therefore, the helping behaviours of those who provide informal help to these students need examination. This study examines the helping intentions of undergraduates in Sri Lanka towards their depressed peers and the correlates of their helping intentions.MethodThe undergraduates were presented with a vignette of a hypothetical depressed undergraduate. A total of 4442 undergraduates responded to an open-ended question about how the person in the vignette should be helped if this person was someone they knew well. Their responses were coded in reference to established mental health first aid guidelines. Logistic and linear regression models were used to examine the predictors of their helping intentions.ResultsThe undergraduates’ most common helping intentions were to listen/talk and support their peer. Only around a third considered the need for professional help. The overall quality of their helping intentions was poor, but better among those who recognised the problem as depression and those who had less stigmatising attitudes. There was some evidence that certain helping intentions of the undergraduates which were person-oriented or social network-related were better among females, those in higher years of study and among certain non-medical student groups. Intentions to encourage professional help were better among those who recognised the problem, but poorer among those with personal experiences of this problem and among those who perceived this problem to be a weakness and not a sickness.ConclusionsAlthough the undergraduates may attempt to support their distressed peers, they may not show appropriate helping actions and may not encourage the use of professional assistance. Hence, they need to be educated on how best to respond to their distressed peers. Those with higher levels of stigma and inability to recognise the problem may be at greater risk of showing poorer helping responses towards their distressed peers.Electronic supplementary materialThe online version of this article (doi:10.1186/s12888-017-1192-7) contains supplementary material, which is available to authorized users.