Disabled children and their families sometimes wait for up to a year for aids such as wheelchairs, a social care watchdog review has found.
The Care Quality Commission (CQC) found there were considerable variations in services provided in England with the national average wait for powered wheelchairs at three months.
The Commission said there were also delays in other services such as speech and language therapy and physiotherapy.
The national report and 151 local area reports also looked at the quality of support for children and young people including individual health action plans, whether Primary Care Trusts (PCTs) involve families and children in the delivery of their care and whether families had access to short breaks.
Families felt access to and involvement in services was a challenge and that they waited too long for access to services and for initial diagnosis, the review discovered.
But there appeared to be significant disparity between the negative experiences of disabled children and their families and the data supplied by primary care trusts, which showed high levels of access and care.
Around half of PCTs reported specialist services such as physiotherapy, speech and language and occupational therapy were always or almost always coordinated with other services and 62% said they involved disabled children and their families in the training and evaluation of people delivering their care package.
Other survey data showed the national average wait for a referral for community physiotherapy was seven weeks, with some children waiting up to six months and the average wait for a referral to a community occupational therapist was 15 weeks with the wait ranging up to two years.
Public Health Minister Anne Milton, reacting to the report, said that long waits and frustration for many families was unacceptable and the Government would take action.
"We expect the local NHS to have the services in place to meet the needs of their local population - including fast access to motorised wheelchairs," she said.
"That is why we are taking a radical new approach to integrate services across a child's education, health and care needs. We will set out our plans on this shortly."