This month's referral to treatment times in Wales have shown a large increase in the number of patients waiting over 9 months to start a course of treatment.
Referral to treatment time is the period of time from referral by a GP or other medical practitioner to hospital for treatment in the NHS in Wales.
The figures show that in April, 12,795 Welsh patients had been waiting for 36 weeks. This is an increase of over 2000, or 20%, since March.
"These figures are very worrying," said Kirsty Williams, Leader of the Welsh Liberal Democrats. "The Welsh Government has a target that not a single patient should wait over 36 weeks to start their treatment, yet this huge increase shows things seem to be getting worse not better.
"The Welsh Labour Government should think of the patients behind these figures, many of which will be in a lot of pain and discomfort. For those people, 36 weeks must feel like a lifetime."