Overall satisfaction with the transport provider is down from last year's record high of 90% to 87%, the latest National Rail Passenger Survey found.
Meanwhile, 52% of passengers quizzed said they were satisfied that the price they paid for their ticket was value for money, down by one percentage point from the autumn 2012 survey.
ScotRail stressed its performance in this area was "steady" against a decline across the UK, adding that customers appreciated its work to remove fare anomalies and provide free WiFi on services, as well as its decision to freeze off-peak fares.
Satisfaction with the punctuality and reliability of trains was also down, with 82% describing ScotRail's performance on this as "good" - a drop of five percentage points on 2012.
ScotRail managing director Steve Montgomery said the drop in satisfaction had come as no surprise given that customers had previously experienced record high levels of punctuality and reliability.
He said: "Disruption affects how people feel about rail travel. While two in three delays were not of ScotRail's making, customers rightly expect us to take the lead in delivering industry improvements.
"We will continue to help Network Rail reduce their track and signalling failures, as these have had the biggest impact on our services.
"For our part, we will continue to focus on improving the reliability of our trains, so that the vast majority of services are able to operate with the full complement of carriages."
Overall, ScotRail said the survey showed it had improved in 16 categories, compared to an average across the UK of three.