NHS Fife missed the 18-week waiting time target for adult and children's mental health services between October and December last year.
The Scottish Association for Mental Health (SAMH) says around one in four kids and young people across Scotland were turned away from specialist mental health services.
That figure was previously one in five.
None of the country's health boards met the waiting time target, that is 90% starting treatment within 18 weeks, for adult psychological therapies, with only five doing so for children and young people's services, according to Public Health Scotland.
Fife Health and Social Care Partnership says it continues to make dealing with children and young people with the most significant mental health needs a priority.
Jo Anderson, SAMH director of external affairs, said: "Young people deserve the right to get help the first time they ask, without fearing that they will be turned away.
"And the need for quick access to psychological wellbeing support has never been greater."
The partnership says Fife Child and Adolescent Mental Health Service is continuing to work on making improvements to the responsiveness of the service and delivery quality.
The partnership also points out there was an average of 680 referrals a month for adult psychological therapies and while that referral rate dipped last year amid the pandemic, it is returning to levels seen before the coronavirus crisis.
A spokesperson said: "Currently the majority of people referred to adult services for psychological therapy are seen within 18 weeks - 76% in January (the most recent data).
"The people who are waiting longer than 18 weeks are those who require long term specialist or highly specialist interventions in some clinical specialisms.
"Service developments to reduce waiting times for these patient populations were disrupted by the impact of the Covid pandemic and the need for staff to respond to demand in emergency mental health services.
"However, they are now being progressed.
"In addition services have recently completed a detailed modelling exercise which has identified the resources required to ensure that demand for all forms of psychological therapy can be met in future and that the needs of people currently waiting over 18 weeks can be addressed as soon as possible.
"The findings from this modelling exercise is currently being reviewed to decide how best to address the remaining gap between demand and capacity within some PT services."