The purpose of this thesis is to describe utilization patterns of professional health care (PHC) services reported by youths and young adults (adults) with chronic, complex physical disabilities of childhood (CCPDC) in Ontario. This secondary data analysis used data from a survey of 193 youth and 97 adults with cerebral palsy (CP), spina bifida (SB) and acquired brain injury of childhood (ABIc). Frequency of PHC services was examined from access-to-care and organization-of-care perspectives from the prior year. Youths and adults were equally likely to see a family physician. Although both age groups had high needs, there was a statistically significantly lower rate of use by adults for Specialist Physicians (OR = 0.28), Physical Therapists (OR = 0.13), Occupational Therapists (OR = 0.14), Speech Therapists (OR= 0.33) and Dentists (OR= 0.32) when compared to youths. The greatest difference in use occurred in those PHC services that are not government funded in adulthood.