The number of patients waiting longer than 36 weeks to begin NHS treatment has more than tripled in the past four years, figures have revealed.
Numbers rose from 7,434 in September 2011 to 25,373 in June 2015.
The figures, obtained by Plaid Cymru, also showed the percentage of people waiting at least 26 weeks increased from 8.5% of all patients to 15.2%.