Only 56% of ScotRail passengers say they are satisfied with the service, according to a Which?
survey of rail travellers.
The company came seventh in a list of the UK's 19 rail operators, which saw the majority of firms score below 50% satisfaction rates.
The results were based on satisfaction with a firm among regular travellers and whether they would recommend that company.
The results contrast with the independent National Rail Passenger Survey, conducted by Passenger Focus, that showed 90% of passengers were happy with ScotRail's service.
Passenger satisfaction with Virgin Trains was 64% in the Which? survey, while 59% of East Coast passengers were satisfied.
The survey found 16% of all passengers had been delayed on their most recent journey, with this figure at 26% for commuters.
Across the UK while 11% said they had cause to complain about the last journey they had taken, three quarters did not.
Which? also asked what passengers felt would improve their journeys and for what they would be prepared to pay more.
Lower ticket prices were top of the wanted list (60%), with 80% saying fares were too high. People also wanted to see more carriages at peak times (35%), promotions on ticket prices (29%), wi-fi (20%) and better reliability (18% - rising to 29% for commuters only.)
Richard Lloyd, from Which?, said: "It's disappointing to see some train companies consistently falling down on the basics of customer service, with dirty and overcrowded carriages and toilets that don't work.
"Seven rail franchises end in the next two years and we want to see passengers' experiences put right at the heart of the tender process."