About 90 per cent of the DHB's senior doctors belong to the association, said its executive director, Ian Powell.
Ten out of 25 members responded to the first survey and seven to the second.
Mr Powell said those running Wairarapa and Hutt Valley hospitals needed to take action: "The people of Hutt Valley and Wairarapa are not being well-served if their DHBs fail to involve doctors fully and properly before making decisions."
He said both DHBs were in serious trouble and sharing a chief executive, Graham Dyer, was "unwise".
"Some of this poor performance is due to ill-considered, politically driven, top-down restructuring.
"But some is clearly due to a combination of poor leadership culture and performance."
Most respondents believed management wasn't genuinely committed to letting them have a say and Mr Dyer was working to "no extent" to allow them to take part.
Mr Powell said it mattered because senior doctors understood the level and type of health services needed in their communities.
"They should be having significant input into any discussions about what is needed locally or regionally."
Mr Dyer said the DHB was committed to strengthening and improving engagement.
"While we may question the results of the survey with such a low response rate by senior medical officers, we are taking the results of the survey seriously."
He said as the association noted, there had been major change. In July last year, the two DHBs began sharing a single management team.
"Whenever this occurs there is an associated level of uncertainty as new relationships are formed. The surveys undertaken by the association occurred within months of the implementation of these changes and we believe they reflect this uncertainty."
They had regular catch-ups with senior clinicians.
"The Chief Medical Officer and I are making a conscious effort to meet staff and attend their meetings to give them opportunities for discussion, feedback and input."
Mr Dyer said they had tried to engage with the ASMS, inviting it to executive leadership meetings alongside other unions. "While most other unions have openly engaged in this process, the ASMS have generally declined."
Nationwide, more than 60 per cent of those surveyed said they didn't have time to be involved in decision-making.