Sex offenders at Peterhead Prison could pose an increased risk of reoffending on release due to not getting access to treatment, it has been warned.
Almost a quarter of the inmates have been recalled after release over breaches of supervision.
HM Inspector of Prisons Hugh Monro has now called for all prisoners to be better prepared for release.
Conditions in the jail are among the worst in Scotland, the HMIP report also said.
Sanitation and hygiene arrangements were of particular concern.
A new HMP Grampian jail, due to open in Peterhead in 2014, will hold about 500 inmates and replace the two older Victorian jails in Aberdeen and Peterhead.
In the report, Mr Monro said: "Given the specialist nature of Peterhead I am concerned about the insufficient provision for addressing offending behaviour and the small number of prisoners who are appropriately prepared and tested prior to release."
He also said: "Conditions in Peterhead Prison remain among the worst of any establishment in Scotland."
Mr Monro added: "My inspection did find many positives in Peterhead Prison with a total of 16 examples of good practice, the majority of which are a testament to the dedication of staff and management who have continued to deliver under difficult circumstances.
"The fact remains however that these are all overshadowed by the very real issues surrounding the age and fabric of the establishment."
Justice Secretary Kenny MacAskill said: "Brigadier Hugh Monro's report carries welcome praise for the staff at Peterhead and acknowledges good practice in a number of areas.
"The SPS has significantly reduced the population of Peterhead recently to ease the pressures on accommodation and to improve conditions.
"The fact is that HMP Peterhead is not a modern prison - it is a product of the Victorian era and is no longer fit for purpose."
He added: "We have invested record amounts to bring prisons like Edinburgh, Perth, Glenochil and Polmont Young Offenders Institution up to modern standards after years of under-investment.
"Only last week SPS submitted its planning application for a new community-facing prison at Peterhead, HMP Grampian."