Supply teachers transferring from Berkshire County Council to Wokingham District Council are having to formally re-apply to teach in the new authority, unlike permanent staff.
The council's medical questionnaire predates its new role as an education authority, and is sent to everyone offered a job. Teacher representatives say the form is "intrusive and bizarre" and could breach equal opportunity legislation.
The form asks 40 detailed questions, ranging from "do you have a speech defect?" and "do you bite your nails?" to "have you ever had an HIV (Aids) positive test?" and "do you smoke cannabis or use other substances?".
Women are asked if they have suffered from pre-menstrual problems or any breast or gynaecological disorders, and to give the date of their last period and smear test.
Dick Boland, the National Union of Teachers' regional secretary, said supply teachers who had already gone through medical checks should not have to repeat the process. "This (form) does seem to be considerably more intrusive than needs to be the case. If this was used to decide employability, it could fall foul of the Disability Discrimination Act," he said.
Jennifer Moses, equal opportunities officer for the National Association of Schoolmasters Union and Women Teachers, said it was "absolutely appalling" and contained a large number of questions irrelevant to fitness to teach.
Sarah Shepherd, a spokeswoman for Wokingham, said the questions were necessary to cover all potential employees: "The purpose of the questionnaire is to see if a person is fit for the job. It is sent back to medical specialists. We don't see the answers - it's confidential."